There is no functionality in FamilyEcho to combine two family trees, but it's a fairly common thing to do, and there are other utilities that can help you combine your mother's and father's branches into one tree. I haven't actually done this before, so I don't have any recommendations, but if you google "merge GEDCOM files" there are lots of leads. I did look at the first site that comes up when I do that search, and twile.com could not import the GEDCOM file that FamilyEcho created. Since the FamilyEcho GEDCOM file has worked fine for me with other software, I'm going to assume that something is wrong at twile.com.