DW and DD arguing

[topcat2014]

DD is 19 and back from uni. Bright and sociable, but sometimes a bit chaotic. She's apparently lost her retainer and the cast to make a new one. She loses other important stuff as well.

So far so normal.

Thing is DW and DD argue and DW cannot move on.

I don't know how to de escalate

DD is ringing the orthodontist tomorrow. I feel a bit sorry for DD as (hard as this is to say) DW doesn't really give the impression of liking her very much at the moment.