seeking advice on sweet chestnut trees

Hello permies!

I have a question for those of you who have experience with sweet chestnut.

A few years ago I planted about 20 sweet chestnut trees.

The results haven't been great, but then they could have been much worse. Of the 20 trees planted, only 5 have survived and grown - but that in itself is a miracle in my view, given the unfavourable circumstances:

- planting from pots, hence starting with a root system that was less than ideal
- heavy clay soil
- no watering for the first 2 years after planting (as I wasn't living on site at the time)
- vole pressure
- very cold winters, hot summers, full sun exposure

The good news is that thanks to manuring and wood chip mulching for 2 years in a row, the surviving 5 trees have finally started to put out some decent growth - up to 60 cm in a season. That's big progress from only 10-20 cm in past years.

For some time, all of these trees have been putting out sprouts from the base, which have been growing a bit faster than the parent tree (although they're not by far the same height yet). I think the original trees were seedlings, so the basal growth should be the same as the parent tree.

So far I've been very hesitant to remove the sprouts, as initially the trees were not promising at all, and I thought that if the tree died, the basal growth might live on.  

So here's my question: I was wondering whether in order to speed up growth I should...

(a) remove the suckers to save the tree's resources, in the hope that the tree will grow a bit faster; or

(b) remove the parent tree, which would leave me with something similar to a coppice stool (several sprouts around the stump of the cut tree) - in the hope that the basal growth will perform much better with the parent tree removed; or

(c) remove the parent tree and all of the sprouts except the strongest one, to replace the original tree; or

(d) keep everything as is and make a decision later (at the moment the plants look a bit like bushes, with the mother tree in the centre and the basal growth around it).

I would be grateful for any advice or suggestions!

your chestnut variety is probably different than what I have, but I just let them grow, when they start producing nuts then maybe I'll think about pruning, but for the mean time I just let them do whatever they are going to do. one reason I started growing chestnut trees is that it is what I want to call a wildlife species it will grow naturally in a forest without any attention or manipulation. much different than fruit trees that need all kinds of special attention to produce a good crop.