Are the two pied geese both girls? I was going to say you have to separate ganders in breeding season but then it looks like you've got only one gander and two geese? I'd keep an eye on the situation. In theory you should be able to have one gander, two geese and he should look after both of them. If it doesn't work out, yes, you'll need to rehome her because geese need other geese really (apparently in Switzerland it's actually illegal to keep a solitary goose) so it wouldn't be fair to keep her with the chickens long term.
H