I have a very pretty 'Bridal Wreath' - can I divide the plant to make more???
Is this the shrub that's a cultivar of a spirea? Has it got more than one stem coming out of the ground?
If you mean the shrub spiraea then no, you can't split the stem and roots but you can take softwood cuttings in summer to make new plants.
Many spiraeas sucker and produce new plants from spreading roots. If yours is doing this you could dig up the suckered shoots and either replant straight away in well prepared soil or pot them up in good quality compost and grow them on till you're sure they're OK before planting out in your borders.
Sorry, should have said proper name, yes it's spiraea. Actually my neighbour cut his back, then chopped it in half, and it's thriving. However, not sure I wanted to take the risk if it wasn't the correct thing to do - and kill the poor thing