dnd 5e – How to breed / tame / tame monstrosities and other creatures

Note: I'm not interested in TRAINING but in the process of DOMESTICATION of creatures whose descendants will be used for training.

Game Dwarf and as my background story I have a self-named search to find a creature that can be more useful in the mines.

As a druid, I resist (I do not want) to take the beasts to the mines and, therefore, I decided to study mainly the monstrosities, and also some giant lizards as bread to assemble after seeing them mounted by people of lizards.

I know that this is a long and tedious process that can take several generations of animals to have success. Currently I have only met umber hulk

Also the white creature would be good to use in mines and what?
Enough cargo, tunneler, guard.