WooHooless? I have two Sims, both married with 100/100 meters. I was trying to get another child to compliment the one their grown-up daughter had. There are only Six Sims in the household, yet they can't "Try for Baby." Does this have anything to do with a game error, or is it natural for them to loose that ability after their child turns to an adult?
You mentioned that they have a grown up daughter...so I'm assuming they are close to becoming elders? The game won't allow a female sim to "Try for a Baby" when they are about 4-5 days away from becoming an elder. Check their ages...if she's too close to becoming and elder than get the aspiration reward that looks like a sand timer on a stand filled with green liquid. If she drinks it when in platnium mood it will add 3 days to her age so she should then be young enough to "Try for a Baby"...if she's still not young enough just have her do it again!
Actually, because her daughter was a teenager when I started with her, she's only 17 days old. Could it be that her same daughter also has another baby on the way.
Only if her daughter is having twins... You said there are 6 sims in the house and if the daughter is one of them and is pregnant then she must be having twins. 8 is the limit and the twins odds are set at conception. If the mom is still young enough to have a baby then that's probably what's going on. If the daughter was only pregnant with one baby then there would be the option to try for a baby for the mother. Have fun when they arrive!