Hello from Germany.
I think there is another error in the kinship report:
Brother-in-law/sister-in-law are only generated by my own sibling’s husband/wife and not my spouse’s brother/sister. If there are no siblings, no brothers-in-law are generated. The same applies to the husband’s/wife’s brother-in-law or sister-in-law, or “Schwippschwager” in German.