When I click on a sim Try for baby is dimmed out. Hoovering over it it says Progress Denied. The couple already have children created in earlier version of NRaas mods.
It's not on all sims. The actual case is an alien family.
I forced a pregnancy with "Instant baby" in MC without problems.
Try for baby = Progress Denied
The Teen-Adult one is most likely resolved this way : StoryProgression FAQ Caste
As for the Near Elder check : You could turn off "General \ Check Story Progression For User-Directed" in <a class="wiki_link" href="/Woohooer">Woohooer</a> and get pregnant anyways if you want.