I tried but in vain. The system wouldnt recognize their application numbers/ uci’s. Only mine got linked when i plugged in my pr application number mentioned on photo resubmission letter (i was the primary applicant under express entry).You need to link PR card application separately for each member of your family.
Even at the airport, when we did our landing, the officer did not mention any such thing with regards to creating an online portal/linking application. I hope they send the pr card for all three of us.