Xbox gold issue - cant share

I have had Xbox Gold for several years and I share my subscription with another family member in the same household. After recently changing my email (three days ago) my other family member is no longer able to access games online using my Xbox Gold account.
I have assigned myself on as the home Xbox for the other family member and signed their game are tag as their home Xbox on my console. Despite several attempts The other family member is asked if they would like a gold subscription every time they try and
play on a game online whilst I am using my console at the same time. I have cleared the cache on both X boxes and powered down both X boxes in an attempt to make this work to no avail. Nobody at Xbox will speak to me on the phone and I am unable to get through
to an agent by the website. I am wondering if something needs resetting on my account so this is something a gamer/helper can not rectify. Can somebody please help as it’s very frustrating and I’ve been trying to sort this now for two days. I must say I’m
not really impressed with the customer service from Microsoft either. I thought it may be down to the fact they are change my email address but obviously that was now three days ago so I’m not sure what else it can be .Thanks in advance

:)