Wow, eta, maybe you are indeed of Welsh extraction--cool! But according to the site I put above, you'll have a heckuva time doing genealogy. I found a dictionary site where you can enter a word and have it bring it up any word that it's a part of; nothing on grw by itself, but here's the page**--I like the purr version, myself!
http://oldweb.cs.cf.ac.uk/fun/welsh/LexiconForms.html

**Ok, just did a preview and found that it won't let you go to the specific page, just the opening one. Type in grw and set it for Partial word.