In house Interlining

Question

Does a subsidiary and a holding automatically have interlining? How about 2 subsidiaries interlining with eachother?

Thanks  

No, you have to interline with the subsidiaries you want to.

A = holding

B = A subsidiary

C = A subsidiary

Is legal:

Interline A and B?

Interline B and C?

Every interlining within the same holding is legal.