Salam, 

Thank you for trusting me with your question. I understand that there are many different opinions on this matter and it is something that can cause a lot of anxiety for converts with non-Muslim families. 

I believe it is up to each of convert/revert to Islam to navigate these Christian holidays such as Easter and Christmas as delicately as possible. On the one hand, we do not want to participate in the shirk and haram that many traditions surrounding these holiday entail. But we also do not want to damage the ties of kinship. 

It is up to each convert to Islam to make this call for him or herself and what is right for their situation because it is only you who will know how your family will react to your absence if you choose to not join them. And only you will know if they will pressure you too much to do the haram on these occasions. 

If you can stay away from the shirk and haram that is done on these occasion then joining your family on this day is something to consider. Because if you are simply sharing a meal with family and your intention is to keep good ties, then inshaAllah there is no harm if the day just so happens to be a Christian holiday. 

I hope this helps. 

Salam.