hello again d m, from your "post" it looks as though you have received other info about your family , or at least about the area, which is good news. I have been re-reading all that my husban's cousin discovered, but please bear in mind that this was in 1976! long before internet access to Ancestry. co .uk !
So before I tell you what I know , I can tell you that I went to family search.org last night & found the record for the marriage of William Mclandsborough( they kept changing the spelling,just to confuse future researchers!) & helen Grierson . It was 18/6/1797 at Irongray church.& also on that site was ,a record of baptism for janet Mclandsborough on 20/10/1803 (same place). Was she your
gt gt grandmother?
If you don't already know of that site , it's certainly worth a visit. so to try & prevent you going off at tangent with all the Landsboroughs Mc's & landsburghs, I think you should stick with the William Landsborough line, as he is your direct ancestor ,as he was Janet's father. John & jessie L are my husband direct ancestors, as is Robert Maxwell. So I can't help you with the Taits & Carsons , I'm afraid ,but if you want to go back from William & Helen then I have lots of information there.