You can share your invidyo account with as many friends/family members you like.
Please keep in mind that you are not able to share individual cameras. If you share your account with another user, you give them access to all your cameras.
In order to share your cameras with a new user, go to camera settings screen by clicking on the settings button in the upper right corner of your live viewing screen (EVENTS tab).
Then, expand the Share Account tab. There you will see the Add New Person button.
Click Add New Person and enter the e-mail address of the person that you want to share your account with.
Once you click share, an invitation will be sent to the e-mail address that you have specified. The user will be added to the list of users that can access your cameras, and their status will be shown as 'Pending' until they accept your invitation.
You can cancel your invitation anytime, regardless of whether your invitation has already been accepted or not, by clicking on the trash can button next to your camera.
If another user has invited you to view their cameras, you will see the e-mail address of the inviting person in the Section "Users who shared their cams with me". You can click accept and start viewing their cameras or you can simply reject their invitation.
IMPORTANT: If you accept a request from another user sharing his/her cameras with you, this will also give them access to your cameras. That is to say, sharing accounts is equivalent to merging accounts. Once you accept a sharing request, the sharer's account is indistinguishable from your account. Only accept shares from people you know.