I have William, b. 1791 Giles Co., VA as son of William Tiller & Rachelor Sanders per "Blankenship Ancestors" written and published by Gayle King Blankenship 1995 page 244. Not clear on her sources. I agree that Samuel could be a possibility but I have found Gayle an to be an excellent source.
I have marriage date for your "Ira Tiller & his wife" as 3 Sep 1839 per William & Rebecca & Louisa Tiller family bible.
It appears that William & Rebecca Tiller family must have been in Ohio for a while as their son, Anderson Tiller (b. 16 Dec 1810 [family bible])said in 1850 & 1860 census he was b. Ohio. Ancestry.com shows a 200 acre land warranted to a William Tiller 12 Nov 1812 Still studying this.
Also it appears that William Tiller did not have a 3rd wife, if you e-mail me at email@example.com I think I can clarify - it's kinda complicated to go into on on this post.
Appreciate any news on your end. Brad Peck Phoenixville, PA