Companion plants for Elderberry cuttings (planted this year)

I'm just starting out and have planted 24 Elderberry cuttings, 8 each of 3 cultivars. I was wondering if there are any companion plants that would help the elderberries but not out-compete them? Or maybe it would be good neighbors for the elderberries? I was advised to plant them at least 4 feet apart with 12 feet between the rows and to plant the rows to facilitate wind pollination. That's a lot of space that I'd like to use wisely perhaps on the order of the 3 sisters. Does anything come to mind?

My elderberries are still in pots but my plan once they get into the ground is to underplant with a layer of edible/medicinal groundcover species. Thinking mints, strawberries, walking onions, clovers, etc. I would think any herb that likes similar living conditions would do - somewhat rich soil and medium to wet moisture? I would plant the Mediterranean herbs elsewhere.

Alliums seem to be a go to for companions.
I find that onion sets and starts do poorly when left to their own devices, but as long as you plan on weeding and watering, they might be fine.
I often plant onions I find in dumpsters and they thrive on neglect,producing both green onions and big flowers.
I would suggest beans or greens but either of these is liable to tower over the cuttings pretty quickly.
A crop of daikon could provide greens, seed pods and soil improvement.
A crop of sweet potatoes can be used the same way, but they might climb.
I planted squash with my cuttings but I can't recommend it.
My cuttings have mostly died, as has most of the squash, but there are many variables that could account for that.

For the borders of your beds, comfrey is a natural choice.
I'm also  gonna suggest Illinois bundleflower also known as  prairie mimosa.
They make tiny edible beans, fluffy flowers, lacy foliage  and dappled shade.
They never grow very big and they leaf out late, so they won't suppress your elderberries.
They wont suppress anything else either, so maybe add some alfalfa.

Yarrow would be good too

Ajuga is another perennial edible that could work

I have strawberry which does great, and things in the onion-garlic-chive family. Garlic mustard greens also seems to do well too, I do zero work and it reseeds itself every year.

Right now, I'm trying my hand at rooting cuttings from the ones originally on my farm near the house.  I'm moving them to new locations that are wet sometimes, but not all the time.  I initially give them a wide area of mulch and we'd a bit the first 2 years.  By year three they are often taking over and what ever grows around them fills in.  I may have to abandon the original patch, it's being taken over by Sumac.

I suggest some queen Ann's lace or yarrow for attracting small flying insects for pollination.  My berries seem to be pretty space on their umbrella or Florence's or whatever you call them

Suggest researching the behaviour of garlic mustard in your region before considering planting it. In some areas it becomes an invasive weed that readily naturalizes and outcompetes native understory plants.