My wife is Indian citizen with us permanent residence. She would be travelling from Delhi-Frankfurt_London-Chicago with small layovers at London and Frankfurt. As Germany is Schengen and London is non-Schengen, would she still need transit/visitor visa? I know for Indian citizens with US residency, transit visa is not required if there is a single layover in Europe. Also visa is required if there is more tahn one Schengen lay over. What about this one Schengen and one non-Schengen layover?
If I need a transit/visitor visa, do I need for Germany or UK or both?