Adult yuri couples living fluffy lives I what I like the most, instant favorite.
Are there any yuri manga were they're also parents?
I can only think of Nanoha, you should be able to find a couple dozen of English doujins where their family is the focus, because in the official manga the yuri and the moms are not as prominent as in those doujins, they take a backseat after StrikerS.
Are there any yuri manga where they're also parents? Closest thing I can remember are some Sailor Moon doujins.
The tag for science babies has some. Sailor moon doujins has some (with Neptune and Uranus parenting Saturn, mostly with Pluto helping out). One of the chapters of Sweet Guilty Love Bites has a single mom falling for a day care teacher. There's not a lot, but it exists.
I love adult yuri, married with a small child is the best. The adult life tag needs more attention
For real. It's a complaint I have about anime and manga in general that it's so rare to see adult leads. This manga was particularly cute.
Its down to the old rule of storytelling. Ask is this the most interesting part of a characters life if not then why are you writing about it. In Japan and most other places around the world once you get out of school your life becomes very very boring. As such you need to do something to make it interesting or at the very least entertaining.
Just working off raw cute will only get you so far and being funny gets more and more difficult the longer the series goes on. A good example of how to do domestic stuff right is dragon maid where its funny weird and interesting. Its a shame because adult stories done well can be amazing.