There is no need for the thread to be re-opened if you will be donating the $400 to her anyway
Im sure she will appreciate the additional money from you though and you are to be applauded for your contribution.
I didnt have any issues with you donating the additional $400 to Sarah rather the insensitive way you went about it but thats all in the past as far as i am concerned, either way Sarah is $400 better off thanks to your generosity
Regards,
Lee