If it was that easy everyone would do it. The address you give has to be yours or it is fraud. If the bike is stolen overnight fro ma different address than the one you gave expect to have a good reason why it wasn’t at your home if you want to get a payout etc. Any false info you provide will be used as an ecxcuse to invalidate the policy. If on the other hand you genuinely store the bike with relatives, and make that clear to the insurer, you may get a discount.