Hey @Ap85.
Right now, all members of the Premium for Family plan must live in the same physical address, as stated on the T&Cs.
If you're living in the same address, try clearing your browser's cache and cookies or using an incognito window to invite them, and accept the invitation.
All the best.
“Music acts like a magic key, to which the most tightly closed heart opens.”
― Maria Augusta von Trapp
