Hi,
Please have a look at this:
My family is planning a visit to the US, which have issued them visas that are good for six months and expire by the end of the year
This is a mistake correcting exercise and I choose “have” and change it into “has”. But do agree this is an ambiguous sentence? I mean: it’s hard to understand who/what “issued them visas”, right?
It should be:
My family is planning a visit to the US, which has issued them visas that are good for six months and expire by the end of the year.
Break it down into separate sentences:
My family is planning a visit to the US. The US has issued them visas. The visas are good for six months. The visas expire by the end of the year.
As for whether or not it’s ambiguous, I don’t think so: The first “which” must logically refer to “US”.