Generally would be identified as M.F. Christensen, rather than just Christensen.
M.F. Christensen came first, then Christensen Agate. Not related except I that that the 2nd company picked the name because it was a famous marble name. M.F. Christensen is best known for their handgathered slags with the 9 and tails.
On the other hand, Christensen Agate did have some handgathered marbles, presumably including slags. Akro also had handgathered slags. Peltier did too. Not sure who would know how to sort through all of them.
Long story short: Good chance of MFC on many handgathered slags. Some possibility of other makers. I would start a "handgathered slag" section and show them off without worrying too much about if they are all MFC.
NOW ... to your specific marbles. Top row all look handgathered. One the middle row, I'd like to turn over the left one and middle one to see if we really have 9 and tail action there. On the bottom row, I'd like to see more of the tail on the middle one. Finally ... on the bottom right ... I'd like to see more of that one for a different reason -- to see if it could be a cork or a transitional.