my dear, you need to think of you too as you do these things; easier said than done, I know... I just finished shampooing my carpeting - have my bedroom left, but after Thanksgiving for that... but my right arm is about to break off right below the shoulder!!! The shampooer got heavier with each push and pull............. now on to your problem.
Send a very pretty Christmas card and an IOU decorated real pretty (maybe using another Christmas card as a cutout) and if they know they are getting a quilt from you - send a picture of it - so they know it is in progress! They will understand. I did one for my dgd one year and my dgs felt left out so I promised him one the next year, and he is such an understanding little man - just 8 years old, and when he got his he was so much more appreciative of it... and cuddled in it in my lap even though it was single bed sized!!! So, although things do not get done in time always and we feel bad, children do understand more than we give them credit for - and a Christmas IOU is such a cute idea to help solve the dilemma.
So, happy sewing, take breaks, (and medications) and enjoy the moment! Best wishes from another quilter...