If I recall I think you need to be linked by the same owner. Since you do not own it then it probably wont allow. If somehow it is allowed, then you need to becareful. If you screw up your account (ie: pernament suspensions), his account is gone too and vice versa.

So personally, I wouldn't bother with messing around with linking yourself to your cousin since you would be putting your cousin and yourself at risk.

Just attach a credit card to automatically increase your limit to 100 or what ever and then call up every month.