A variant is horizontal - There is a "master", and different versions are made out of it, which are the "variants".
Remember the Steyr TMP? The OIC prohibs the semi automatic version of TMP, which is the SPP. TMP is the "master", SPP is a version of TMP. TMP came before everyone else.
The B&T MP9 is a direct descendant of TMP. From MP9, a new version of the "master' MP9 is made. You can agrue that both TP9 and MP9 are variants of TMP, but they are not variants of SPP (banned).
The argument here is whether the SIG 540 is the "master", or that the SIG 550 is the "master". SIG 550 is a descendant of the SIG540. Is PE90 a descendant of the semi automatic version of SIG540, or a variant derived from SIG550?
This is a question that needs to be answered by Swiss Arms and I think it is exactly what RCMP is looking for in the official answer. Mechanical similarities are irrelevant. It is how the design linkage that matters. Our speculation is useless. It is an answer that needs to be answered by the manufacturer who make and design these things over the last 40 years. They have to look up at their documentation and have to come up with a straight answer. They had given the answer 12 years ago, so we will see what they have to say when asked the same question again 12 years after.
Personally, I think our focus should be put on something we can influence, which is to influence our politicians to remove the roots of the problems, that are, the ambiguity in the OICs and the OICs themselves. Our speculation on the "true" answer of this "variant game" will just end up harming our own cause and diverting valuable engery from things that we can influence.