Hi Madison,
The Ingram middle name in the Thomason family is in respect for the local minister at the time. I have found out a lot about that family but not traced them out of Shetland.
Do you live in Australia as it might be interesting to do an AncestryDNA test when they become available soon (hopefully within a few weeks).
If you are able to tell me a few details about your grandfather I could have a look for you.
Naomi