This really shouldn't be a problem, and in all the years (been a while), that I used BT GPS, I don't recall anyone having this problem. If the GPS radio is on, and available, it should show the com port in the DeLorme program. It should only show an available BT com port, as messing with active com ports on other devices can cause serious problems with those deviced depending on what they are. Not a good idea.
Note: Options/GPS tab will only show a possibility of 2 com ports, normally only 1. With a built in BT radio it should normally stay on the same com port. With a USB BT radio, it will change when you move it between USB ports, so always use the same one. If you move it you will have to change it in the DeLorme program. When you click on the Port option on the Options/GPS tab, it will show the last set com port and the new com port where the radio currently is. If you check your Bluetooth Devices in your OS's Control Panel, it will show the current incoming com port. That will match what the DeLorme program is using, and is the com port to select in it.
I still have a BT radio, but not a BT GPS so, I can't test it thoroughly right now. I just checked the com port settings and found that they were on the high end from the last time I used it. From what I remember, if it's set in Device manager to a high number, then other devices that use comports will almost always take the lower numbers, leaving your BT port high. Once you get SA set to the proper port, it should remain that way, pretty much forever. I used to switch back and forth between a BT and USB receiver and never had to fiddle with the BT port.
This search is using Google (works better than the forums advanced search). I'm leaving it native so you can fiddle with it. If you remove the +retain keyword, you'll get lot's more hits to read through.
http://www.google.com/search?hl=en&lr=& ... f&oq=&aqi=