It appears uncertain whether she is reconciled to or holds Communion with the See or Church of Rome, professes the Popish Religion or is a Papist, which would offend the Act of Settlement. In any event, the chances of the Act of Settlement ever operating to deny the Crown to Peter Philips are negligible, seeing as he is tenth in line to the throne today and will slip to eleventh next month when the Wessex baby is born.
But to answer your question, yes, such a thing has already been allowed. The Countess of St. Andrews, wife of the eldest son of The Duke of Kent, was Canadian, Catholic and divorced, and permission was granted for that marriage.