Make sure they're close to each other, have plenty of space to grow, and are not following anything, then try again.

For some reason it just worked, I was in my base looking at them nothing couldn't do anything, I went and beat the air avenger dragon (I already had a lighting so i wanted to see if they could work together) and i got 2 chibis from it so i thought maybe if i put the chibis for certain dragons in their inventory it would work, after i did that it worked. idk if it was the chibis or anything but it just worked, i didnt move them or make them get anymore kills or move any dinos around them.

edit: I just wanted to say besides a few bugs here and their you did a fantastic job on this mod, and you have probably saved this game for me.

It's not the chibis, lol. Sometimes Ark is just Ark, no matter the mod. :P Glad you're having fun though.

yeah I didn't think it was them hahaha, I was just explaining what happened before it let me grow them up.