Constant Contact API Project

I have 80,000 contacts in my Constant Contact autoresponder. The autoresponder sends out an email based on the amount of time people have been members of my mailing list. Usually, my mail is sent once per week. Currently, I have no way to rearrange my mailings without users getting an email multiple times. Here's an example: Let's say that someone has been a member for 8 days. At day 7 they received an email... call it "email A". If I wanted to insert a DIFFERENT email at day 7 and move Email A to be sent at 14 days, that member will end up seeing the email again. They saw it at day 7, now they're seeing it again at day 14. Now that I have built the autoresponder, I am stuck. I need someone to use constant contact API to allow me to change both the date of email AND the date of entry of all of my contacts at the same time. It would basically give me the ability to move people and emails at the same time so that I can reorder anything that I want. I could space people out and insert emails without forcing people to see them twice. Let me know if you think this is possible.