suckering shrubby paeony

I have a lovely yellow paeony but it's disappearing under Viburnum rhytidopyllum and a large Cotoneaster 'Rothschildianus'.  I don't want to spoil the shape of the 2 large shrubs so the paeony has to move or be swamped. I've tried to get suckers potted up but they die. I've sown seed but it must be a hybrid, what I get is a much taller, non suckering shrub. Perhaps I'll try some hardwood cuttings before I give up.

When would be the best time to tackle a move? It's not going to come out easily, it's been there a long time. Lots of other roots to contend with plus all the half bricks and bits of concrete that are the 'bedrock' of my garden.