Weebly to Squarespace - SiteMap Issue

I'm transferring my Weebly site to Squarespace. I'm attempting to keep the page urls in the same order to make the transition SEO friendly as it is in the middle of our busy season and we cannot afford a dip in Google now. The issue is, how to place the order when the navigation pages are separate from the non-navigated pages. How do I assign a drop-down page from a navigated page?