https://www.curseforge.com/minecraft/mc-mods/the-twilight-forest
Also would be really nice to be able to get the special logs and leaves from the leaf dungeon only saplings.(Those trees don't drop saplings. TImewood, minewood, sortingwood, etc )
And possibly root blocks rarely as well like ol bonsai trees 2 had

Thanks for the request. I've spoken with some of the Twilight Forest developers about this and they seem interested in adding it on their end. If not I can still implement this on my end however I am not very familiar with the newer stuff in that mod so I can't verify if adding those dungeon saplings would break anything.