Ship Set based on request date

Hello

We have a requirement where the ship set we want to base it on Request Date. Currently out of box if we have same ship set the schedule ship date would equal it. However our requirement is let the schedule ship date be different but i want the ship set be driven by request date. So for example if two lines are on the sales order then schedule ship date given by GOP is different we want it to let it remain but base the ship set based on request date? Is that even possible? Has anyone done that? can it be achieved by customization and how?