That's bizarre as there is nothing in the member guide about such a thing for Star Alliance airlines (there is a statement about some codeshares being excluded for other partner airlines). The rules do differ from airline to airline though and some Star carriers are very clear about the rules.
Air Canada is very clear on LH flights: "Not eligible: charter flights and code-share flights operated by any Lufthansa code-share partner other than Star Alliance airlines."
and for BD flights "Not eligible: charter flights and code-share flights operated by any British Midland code-share partner other than Air Canada."