"¿Les interesa a ustedes ir a la fiesta?"
Translation:Are you interested in going to the party?
Yes, both of those are correct.
Someone tell us if we can say "¿Les interesa ir a la fiesta a ustedes?"
The verb is interesarse. Here is how it's conjugated:
interesarse = (mostrar interés por algo) = take an interest in OR be interested in
Siempre me intereso por todo lo relacionado con la moda. = I always take an interest in everything related to fashion.
This verbs is similar to other verbs such as gustar. It's helpful to check out some sources online for how those work.
When there is an indirect object you need les, even when you add a ustedes to clarify who you are referring to.
I used "to go" instead of "in going" but got rejected. That's OK in English where I live although maybe a bit idiomatic.