So I have tested Dad at both 23andme and Family Tree DNA. I just discovered the fun option “in common with” on the Family Finder matches pull-down list. If you select that option then you can see all the matches you share with people whom you have assigned relationships too.
See the orange button labeled “assign” above? Use that to assign a relationship to someone whose match you wish to analyze further. Anyone who you have assigned can then be used as the “member” in the in common with function.
So I used this function to look at a known fifth cousin and found another fifth cousin! We have lots of new cousins back in Norway now. I also assigned an adoptee with a huge match for Dad to distant cousin so I could see what line he is from. He matched a known 7th cousin over at GEDmatch on the exact segment he matches with us but much smaller with the 7th cousin. So now I know he is a Munson from the Kristiansand line.