I must tell you I have been trying to get that out of my garden for 20 years and still keep having to dig it out
It comes up through my groundcover junipers (and every other plant I have), under trees, basically everywhere. The more I dig out the more I get back again. I agree it is very pretty, but there is a strong chance you will regret keeping it. And don't try to dig it...the roots go down underground forever and a day. Roundup would be a better method. I can't do the Roundup in most places because of other things planted around it.