Any ideas what this means?

[kiterunner]

Going through my DNA matches, I am finding that there are quite a lot of matches with whom I share about 16 cM in 1 segment, and who are also matches to my Dad, but sharing only 7.7 cM with him (also in 1 segment). None of them has shared matches so far, though some of them are certainly closely related to each other, but of course Ancestry only gives shared matches which are above 20 cM.

Do you think I can assume that they all share the same segment with me, and the same segment with my Dad, and that they are all therefore related to us on the same line, if I ever figure out what that is? I'm imagining that all those people inherited the 16 cM segment from our common ancestor, and my Dad inherited the 7.7 cM and another small segment (below ancestry's cut-off, think it is 5 cM?) with a bit of DNA from another ancestor in between them, and that in recombination, I got a bit of DNA which happened to match the bit which the common ancestor had in the middle, thus making it back up to 16 cM. Or is that not how it works?

I'm hoping I can find some of these matches on My Heritage to see if it is the same chromosome in all cases, but haven't found any on there yet. Of course they must be pretty distantly related to me.