How do you handle aging with different generations?

With MCC you can be on any livespan, they recommend normal, but I've used long, then you go into settings - set life span duration. You set the number of days. So with 2 week seasons, a sim year is 56 days.

In Sweden too YA would start at 18, but with my way of counting years, there is no way to do that and keep the same birthday (which I really like to do, I make it a holiday so I remember birthdays even between their aging up birthdays). That's why I start YA at 20, I figure in the sim world, that's when you finish HS. 

For me I need to make elders a lot later than 65, as I think they look ancient. But then I use CAS to make adults look older after 50 (and make sure they can't have kids), and then I use it again to keep elders looking younger. 

I play rotationally and play with aging off ( I tend to get very attached to my sim’s ) in my main save and my scenario save, and on Long lifespan.  Some of my sims have aged a bit because of glitches after patches, but never actually aged up.  I have only had a few  sims born in game, and aged one up to infant ( infants are so cute ( at least if you have growing together ).   My families were all created differently, so I do have babies through elders in my game.  Some households are friends, some are nuclear households, some are generational families.  And I have some couples households, and single households too.  a few households have pets. The households are all very different, so I rarely get bored of my save.  I have a couple of families with teens who are young adults ( but I view adults as staring around their 40’s to well into their 60’s ).  I too think it would be nice to have another age between adult and elder.  Since 2014 I have only aged 1 baby to infant…. lol.  I don’t want to miss out on any life stages from how my families were originally created. Many people are wanting pre teens, I don’t know if they will come about.  I may age some of my children if they do bring out preteens, and I plan to age my other 2 babies to infants soon.  And, 1 or 2 newly formed families will have a baby sometime after getting married.    I change my sims hairstyles and clothing every so often as well as furniture sometimes.  Most of my sims I don’t cheat with, so many are self made sims, and have moved over time.  The Goths have gone from Willow Creek to Forgotten Hollow, and will now be moving to Ravenwood ( same house, but the lot increased when they moved to forgotten Hollow and they have a pool ).  I have another couple that will be moving from a city living apartment to a new home in ciudad Enamorsda ( that will make a third move for them as well )., infact many of my 150 + sims in my main save have changed their looks somewhat over time, and live in fancier homes or apartments as they advance in their careers.  I have had 1 death in my main save.  My criminal sim needed to finish his aspiration so he fought with an elder townie until he passed.  He still has his urn.

I have different households, too, so I can play around with all the gameplay mechanics, try new careers and new traits, and at least one of the kids born into one of those households will age up all to elder and die of old age simply because I want to see how that turns out. It's very likely going to be the Ravenwood household because I created that specifically to test the gameplay that came with Life & Death. 

Those are the reasons why a life stage between adult and elder would be nice. We all age differently, and at least that additional life stage would allow us to reflect that to a certain extent. I turned 50 this year and other than my best friend or my husband, I hardly have any white hair or wrinkles. I inherited that from my mom, I think. She's 86 now and her hair is a mix of her natural colour and grey which makes her look a bit younger than she actually is. 

I added a few wrinkles to my two main Sims and gave them glasses, so they already look a bit older. I frequently change their clothes, too, mostly because I like to try something new but also because it doesn't feel quite appropriate for them to wear stuff from the grunge pack at their age 😁

Oh, I really love your idea! Making the birthday a Holiday, way cool. That way it rolls around, same day, every year. All one would have to do is make a mark on a list for each Sim, to keep track of their 'age, as it were. I'm learning so much in this thread.

Hair style and clothing are also useful to denote age. I make certain my teens wear the styles teens are prone to wear, as opposed to a more sophisticated look, a college graduate might wear. If you try cas.fulleditmode, be certain to open the cheat window, first and type in testingcheats true.

Thanks! I played around with that cheat yesterday, and now my Sims look a bit older thanks to a few wrinkles and the glasses 😁 The gray hair doesn't suit my Sim mom, though, or rather, she doesn't look much different because her natural hair colour is a very light blonde. But clothing can go a long way, and I think I'll play around with hair styles, too. And I really need to disable the pregnancy bit for her. She and her husband have five kids already, two of them young adults, so they're too old to have more kids anyway 😁

Since I play an historic game, I have an unpublished blogpost with all the years, birthdays, important historical events and inventions. That makes it so much easier to keep track. The best part of making the birthday a holiday is that I remember all birthdays even if I play rotationally. 

I've tried it yesterday, and I think it's gonna be my new best friend when it comes to changing my Sims' apperances or traits 😁 I have this one Sim everybody hates already, I think I'm gonna give him the new trait that came with the rewards for the cozy event.

I'm still playing around with the parents' hair colours. Hers is a light blonde, so she doesn't look all that different with light grey hair, but any darker shade than that just doesn't make sense when the original hair colour is very light. So I work with clothes instead. She used to wear miniskirts when her kids were smaller, but now that her two oldest daughters are young adults, she's toning down her style. Her husband, too.