I have a number of separate trees, but Ancestry doesn't have the facility to join them together. I have a version of Family Tree Maker which used to sync with the online trees, but no longer.
I ended up exporting them all from Ancestry as gedcom files and patching them together in FTM before copying it back as a new combined tree. Problem is the media files don't get transferred, but the structure should catch any matches.
I imagine the quality of the matches are only as good as the family trees that are on the site.
I sent off my test 2 weeks ago (to Dublin), but it's still not shown as being received. I read somewhere that tests are collected before being shipped on to America in a batch. Hope they haven't lost it.
Rob