Why is wild onion a problem? Eat them! They are root level stackers, maybe also herbaceous level.

Blackcaps are pretty invasive and usually crowd out other plants. Maybe look at the edges for sites to plant other plants. On the north side of the site you could plant some low trees that won't shade much; fruit, nut, or berry trees such as elderberry, mulberry, etc. You might be able to layer one of the invasive herbaceous perennials over the blackcaps; mint, or either the green or variegated form of snow on the mountain, which is edible.

Hello,
Thanks for your reply,
I have trees there. Tall trees. One masive black cherry and a couple of norway maples to the North.
I also have some crabapples. Thye were there when we moved in. The wild garlic(what iot really is) is nasty fiberous stuff.
I have planted mint under it. What is Snow on the mountain?
Smitty