Guilding around existing Autumn Olives

Finding the 7 or 8 Autumn Olive plants on the forest edges of our property is easy now that their silvery leaves are out.

I look at the footing of these plants and see nothing special going on in terms of exceptional growth. Grasses and what not.

Sharing the understory with them are other native and invasive shrubs like honeysuckle, dogwood, and blackberry. These plants have no age context for me, so I can't tell how beneficial their placement next to the Autumn Olive is. Likewise with the tall trees. There is no context for me to judge the full benefit.

So, is it worth my time to guild into these existing N fixers?

I'm going to throw in some comfrey and see what happens.

Any suggestions or experience with planting into existing trees?

I am going to also put valerian around these autumn olives, but I'm going to do it around the drip line. From simple observation, I can see if there is any benefit to being near an autumn olive for the trees nearby, it is when the tree is outside the bushes drip line. When it is inside the drip line of the autumn olive, the tree is smaller than those around it. Just a hypothesis supported by some common sense.

What I will also do is chop and drop those autumn olives that are right in another tree's root zone, thereby leaving OM in the soil and N.