Which software can you recommend to sync data from a FoxPro source to a SQL Server destination?
I don't think you'll find a tool to do this automatically and on a scheduled basis especially if they are geographically remote and the sync has to happen over the public internet. I'd be looking at writing a web service of some sort, which will sit on a server on the VFP side with methods to expose the VFP data, and another service on the SQL Server side to access that web service periodically and perform CRUD operations.
At my company we have data being written to foxpro tables daily, and are synced to SQL Server nightly using SSIS, so for the actual conversion I recommend that.
Getting the foxpro data to your central location could be accomplished by transferring the foxpro files via FTP (we've done this for years), or you could set up some sort of Web Service.