Managing way point for different lakes

Guys, I've confused myself and need guidance.

I'll be fishing 3 maybe 4 different lakes. I'd like to have a set of waypoints I can add to or subtract from for each lake. I have Humviewer installed on my computer. Is it all done from there or will I be deleting them from the unit (598) before going to a different lake? I guess I'd like to have a file for each lake that gets modified as needed after each trip.

Sorry for the stupid question.

I have a number of recordings and snapshots from the testing I did last fall, too. I don't need them on the unit any longer and will delete them. I do have the files stored on my computer if I ever want them back.

Edit to add: I also have HBPC installed; haven't worked with it much yet, though.

I use HBPC, I have each lake on a different card. When I get to a different lake I export old data to card. Take that card out to import to HBPC for updating that lake. Erase all waypoints off of unit, then put the card in for the lake I am on and import. Mark waypoints and don't forget to export and bring into HBPC, before I go to different lake. It is a little Hastle but easier than trying to sort thousands of waypoints to different lakes. Dont ask me how I know this!

I have an 899 and I take my card and download all files to computer. Then I use Humviewer to make a kml file and import each into Google Earth for later viewing (saved in the cloud for viewing on iPhone too). I then place each recording or snapshot in a separate folder marked by lake for my records. I make any changes to my files in Humviewer first then upload any new waypoints or changes I make. Then I take the card to the unit and upload any new waypoints or changes I made then after making the changes I delete the files I no longer want or need as they are on my PC. You cannot delete any files from the card at your PC. You can only delete the old files from the unit. The unit will remember the last waypoint and track numbers for your unit. Good luck and tell us how you did!