Exchange 2010 servers - Change Static IP Address

Exchange Servers :  Mailsrvr – Exchange 2003, and Exch1 and Exch2 – Exchange 2010 connected in a DAG
Needless to say, there’s Exchange 2003 to Exchange 2010 connector
The customer wants to change Exch1 and Exch2 Static IP Address and the DAG Static IP Address
Mailsrvr:      168.100.10.25
Exch1:            10.100.12.52
Exch2:            10.100.12.54
DAG:            10.100.12.56
The customer wants to move the IP Address to the 168.100 .X.X network
My questions are:  Can we change the Exch1 and Exch2 Static IP address without causing issues with the Exchange server?  Can I change the IP Address of the DAG?
Should I move all the mailboxes from the Exchange 2003 server to the Exchange 2010 server and removing the Exchange 2003 server first before changing Exch1’s, Exch2’s, and the DAG’s IP addresses.
If I change the Exch1 and Exch2 static IP address before I move the mailboxes – Will that disconnect the Exchange 2003 and Exchange 2010 connector?
Thank You