So I wanted to give you all the update on how things went. The girls did great! My parents did a great job.
I ended up having 746ml (almost 25oz) for them. I nursed for the last time at 9:30am and got home to nurse her at 12:30am. So I was away for 15 hours total. DD2 ended up taking 580ml (a little over 19oz) with 166ml (5.5oz) left to spare!!
She latched right on and clung to my shirt. I think she missed me as much as I missed her!
Thanks for the advice and reassurances ladies.