So, latest update. Service ontario referred me to the website mentioned earlier in this link and gave me a number to call if it wasn't clear. However, I was at deivetest on Thursday and explained my wife's situation. The person I spoke to didn't see an issue in my wife swapping her seisd licence on just a UK passport. So we're just waiting on the attestation from te swiss embassy and then we'll try to swap for an ontario licence . I'll update in two weeks.
