I was hoping for manga like Happy Yarou Wedding . Where the uke takes care of the seme's kid, and they form a family. or stuff like that.

Maybe Gochisousama by CJ Michalski and Chapter 2 and 3 from Hitomi no Giwaku by Asagiri Yu.. and also Ai no Gebokutachi by Sakurai Shushushu.. Nothing else comes to my mind..

Sekai wa minikuidesu..shika shi! Yūjō, yūki, tsuyo-sa wa ikinokoranakereba narimasen..Tiruendo!

Mainichi Seiten - Has a family theme, but.. it's a little different from what you want.. but it's really good! XD
First chapter of Kiseki no Koibito

Ohh, I've read stories like this~ O_O

Recommendations:
Tonari no Kare is a good one. :3
Best example of a plot like this is in Hohoemi no Nichijou (first story and the sequel) and Naisho de Alleluya.

Those that sort of fit the description:
Complex (Happens once they get older which is like halfway through the manga.)
Takaga Koi daro (Not sure if they form a family but the uke has a kid. ._.)

And since no one mentioned it yet, Passion Fruit no Kaori Tsuki. I havent read this one yet but by the summary it seems to fit what you're looking for. O-O

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Monkeys, always at your service.

Quote from NightSwan

I have to thank you again. It's been a while since I've had this much d**k on my computer. :'3