I don't believe there's a challenge like this already. It's something I've always thought about trying but haven't actually done yet.

The goal is to play each premade family rotationally, working your way through the generations and intermarrying with other premade families until you end up with a sim that is a descendant of all the premade sims. You could do this in a single neighborhood or a megahood if you have one of those.

Extra Challenge Version: You can add a single sim of your own creation and the sim that ends the challenge must carry this sim's last name. If you choose to do this, you must decide whether the men or women in your neighborhood will pass on their last names. You may not have both do so.

Rules:

• Every premade sim that begins the game is considered an essential ancestor to your final sim and therefore must be a direct ancestor to that sim.
• There's an exception for sims who are already Elders when the game begins (although if you'd like to have the old men procreate with younger women and use the Genie Lamp to make the old women young again, you may do so as long as you do it without cheats.)
• You get a pass for sims who already have children. For example, Mary-Sue and Daniel Pleasant already have two children, Angela and Lilith, so they don't need to have anymore. But both Angela and Lilith would be considered essential ancestors and would need to have children that are direct ancestors to your final sim's family tree.
• For sims who begin the game pregnant, their unborn children are also considered essential ancestors to your final sim.
• Your sims may only marry and procreate with other playable sims, not townies or NPCs.
• You must play each family in equal rotation, for example, one week per family before moving onto the next one.
• Sims who are children of the premades do not all have to be direct ancestors of the final sim. For example, if Angela Pleasant has two children, only one of them needs to have an heir and contribute to the challenge. You may kill the other, have them marry a townie, or live a solitary life if you prefer.
• If a child is taken by the Social Worker before they can have children, you may get the child back by having another family adopt them.
• Optional Rule: If any of the premade parents have additional children that do not exist at the beginning of the challenge, they also become essential ancestors and must be direct ancestors to your final sim. So if you make Daniel and Mary-Sue Pleasant have another child besides Angela and Lilith, that child would also become an essential ancestor to your final sim even though Mary-Sue Pleasant was not pregnant at the beginning of this challenge.

Ideally, you should do this without cheating to make your life easier, but I have many mods to make my game more difficult and/or realistic that I intend to use.

I don't know if anyone's out there still playing Sims 2 and interested in the premade families, but I thought this might be interesting to try. If anyone actually succeeds, it would be interesting to see a picture of what the final sim looks like as an adult!

Interesting, but don't know if I can stand playing the originals one more time

You could always create your own custom hood, but with the same number of Sims as Pleasantview divided into the same family units, and see where that takes you.

This does look like it could just happen to me in my BACC in Dodge over time as the town builds up it's population and they start getting married and having children.I'll have to start with adding more families to the town in the early stages though as the population won't be big enough to use just redient families without moving more in for at least a good few generations.This can be an element of my advanced BACC rules.It's rules would apply only in the later stages with the town after it becomes a larger town.

This seems really really interesting! I might /just/ have to try this for an excuse to start Strangetown lmao

Hey, I'm actually playing like this already in my MegaHood, with premade sims, and trying to limit the amount of babies I make! I actually started playing last year. Only on round 3-4 because I have so many households to start with. My goal is to get down to 5 or fewer houses each neighborhood to make the rotations more manageable, so I'm still intermarrying and moving a lot, but I may not want to boil down to one sim necessarily (if I can, I like to maintain the original last names). I also am trying to set a birth control policy since my goal is to shrink down; the loophole though is that if a family has more babies, I adopt them out (or kill them, but I haven't decided on who should be a cannibal yet, haha... probably someone with an edgy or poverty-driven background). I have a giant spreadsheet for this purpose. I also keep a graveyard sheet and an adoption sheet. No one has died of old age yet, but I've sadly lost 2/3 Curious brothers to a freak fire. Pascal Specter (ne Curious) lives on with his alien baby turned bespectacled child, Stellaris Curious, and has an adoptive alien daughter named Jane Smith Specter with his wife Olive Specter (fitting, isn't it? They're both knowledge sims who love ghosts and aliens).

I actually think there was a challenge before using either premade sims or a certain amount of households to start with and where the bloodline/ last name was important to maintain for the end-goal (it may have been a war between two bloodlines or something, where the challenge ends where one bloodline dies out, or when they combine into one sim over generations); I can't find it though (let me know if someone does find it or something similar).

My personal rules:
1 Rotational play every 3 days.
2 "One Child Policy" per pairing. If more than one living child, adopt out or kill (e.g. with the BBQ). Does not apply to pets. If the parents were already pregnant when the game shipped (e.g. Brandi Broke, Sarah Ottomas), if children were already born when the game shipped (e.g. the Smith siblings), wanting to preserve a last name, having twins, or having both an adopted child and a biological child (e.g. Oberon Gossamer).
3 Limit "cheating" to maintain realism. Mods allowed.
4 Try to shrink down # of households gradually through marriages, move-ins, or deaths. Would ideally have 5 or fewer per neighborhood.
5 "Legal" Children= what is displayed on the family tree (so both biological and adopted, dead and not dead), not including children that will be adopted out.
6 Boarding School and Prep School must be unlocked through Private School Admittance. Other schools can be selected normally but should have a gameplay reason for night school or flexi school.
7 Only record skills that are 5 or above.
8 Only record personality points that are 2 or below or 8 or above. For pets, that is min or max or describe in relation to sims that are important to them (parents, siblings, esp. twins).
9 Only counts as partner if they are in love/ going steady/ engaged/ married.
10 Put the name of the parents at the time of birth/ adoption in Generations so you don't have to keep changing it.
11 If household funds are below $1,000, can apply for welfare. Should delete welfare once $3,000+.
12 Round household funds for ease after the 100s place unless they have fewer than $100. E.g. $3,500 instead of $3,521
13 Can record academic/ career milestones.
14 Can only have actual business in Bluewater Village. If you live in BWV, you must participate in some business-type dealings (e.g. selling a good or service) in your household even if you have a job, but the lot does not need an official business.
15 Can only have farm in Riverblossom Hills. If you live in RBH, you must also do some sort of gardening or farming in your household even if you have a job.
16 Only record playable deaths (so pre-existing graves/ urns don't have to be recorded; too much to deal with).

Spreadsheet Screenshot: https://prnt.sc/ut4ps1

It looks like something that adds another element to a Homesteader's or BACC challenge as they start from scratch and slowly build their community up into a larger city over generations and it becomes a multicultural melting pot.