Just playing devil's advocate for a moment, is it not possible, even probable, that this sequence of family members coming to someone's aid originated separately in different cultures?

It would make the link much stronger if we could identify 2 or more motifs that link the different analogues together, not necessarily just between 2 analogues from different cultures, but perhaps intermediate variants to make the links stronger.

A similar idea arose when trying to link Clerk Colvill and Lady Alice. In British versions the 2 ballads seem to have little in common, but once we add in the continental analogues the links of several motifs become much more obvious.