My suggestion, as the mother plant is right there, would be to read up on air layering. I'm just into my second year but pulled one off my Miss Kim Dwarf Lilac last year and it is doing quite well and even bloomed this spring. I've just started layering that top left knob off this one for a little short fatter one for next year(hope). I had roots and removed/potted in 6-8 weeks last year I believe.
East way to get a head start on a larger trunk and the sawn off stump is screwed to a board attached to the box on mine.