Q: Can my “chain” of seven connected cards of my color be a branched blob, or must one be able to trace a seven-card path from one end to the other?

A: Your seven cards just have to be connected to each other in some way. The group can be branched, or a blob, or anything, such that you could trace a path through the grouping from any one card to any other card. The technical word would be “contiguous,” like “the contiguous United States.”