I like this plan :) somewhat on the same to what I was thinking.

After Yavanna sticks with Kili/Saeril and Dis for a bit. Maybe Yavanna might feel bit awkward, being around Dis. Maybe she's reminded of Fili/Thorin a lot and misses Legolas, in the midst of it all.

I think for a few reasons; she might pick to go after the man she loves. She and Legolas are re-united as she finds him and Aragorn. And she sticks with him and the Rangers...the bond between them strengthens :) maybe Aragorn already knows about Yavanna via Legolas. So he'd be happy to have her along.