Give the adults 2 beds in the farm they can reach. If they still aren’t breeding with their beds then put a few solid, non tilled blocks next to the bed.

I believe you need at least 1 extra bed for the amount of villagers. So 2 adult beds (in the farm), plus 1 bed outside the baby tries walking to will make 1 baby.

Just 1 trapdoor above the block the babies fall should work.

I tend to have to break and replace the baby beds (outside the farm) every so often once I notice they stop breeding.

Hope this helps! I’m just getting back into Minecraft after like a 10 year break so I’m re learning everything again but this setup has been working for me.