Hi, on Im008 form can we right sponsor’s address as mailing address? and if we do that, do we need to fill representative form as well?
In general, a mailing address can be anyone at all's address as long as the addressee (here, the applicant) will receive mail there; and no, it doesn't necessarily mean or require using a representative.
Perfectly fine if the applicant receives mail at the sponsor's address, or parent's, or even at the butcher's if that's what works.