Babysit those "little darlings"!!!!
you're in a great position...make the most of the kids...practice..practice..practice.
I would offer to help.them going out to do simple tasks, like shopping running errands with them and their children. You'll become very acclimated and knowledgeable about children. When you can change a diaper, make a bottle and settle down another child simultaneously, you've arrived to Ninja Status. They'll all.adore you...
Believe it or not, you're one of the friends they will be the most grateful for. You keep them in the global loop that they would have otherwise fallen out of. And just say, you want kids someday and need the scoop :) Mom's are always willing to share knowledge.
Baby sit, see if you like it (being around kids), then you can talk about their little ones