Christmas for DD will not be a good one as we risk not really being able to see/spend time with anyone.
How about making it a special one for 'just us'. Children will pick up how they feel about this from the people around them.
Starting to talk about how you will make it a special time together. How it's a pity that you can't see DGM, let's make a special card to send her, to let her know we are thinking of her.
She is also old enough to get involved in helping those less fortunate. A reverse advent calendar, donating one item of good for the food bank. Have a clear out of toys she has outgrown to be donated too.
Let her get involved in decorating her room, maybe even the whole house, together.
Cooking together is another Christmassy thing to do. Mince pies, gingerbread. Could she be responsible for the first course of your Christmas meal. Choose, cook and server it? I'm thinking smoked salmon, slice of lemon on toast
The stand out moment of my life that I look back on were always the things I was allowed to do things the grown ups did. Now of course I can see that it wasn't such a 'help' for my mother, more extra work to let me help but they are the things I remember fondly.
By all means come back here to vent but with her, it's all about how lovely it busy I have a daughter growing up to do these things together.