In the last question for the family member number you need to put correct number. This is most people enter wrong number and can not able to link it.Did you figure it out how to link the GC key?
I am trying it almost everyday nothing works ☹
Does anyone know how to link the GC key when you have application number and UCI?
Sponsor+ co signer(if applicable)+ Principle applicant + Dependent( if applicable).
Do not include sponsor's kid in the family member.