Thanks Eric ... also ...
I think I just figured it out? Simple copy & paste from one project into another. No "import" required.
I opened both projects. Went to Project 2, selected all the markers plus the audio region <cmd>C ... then went to Project 1, created a new audio track and selected it, put cursor at end of Song 1 and <CMD> V .... boom, both audio region (Song 2) and all the coloured markers for Song 2 planted themselves right at the cursor location.
Also, how do you select a group of markers all at once.
LPX 10.3.2, Protools 11, OS 10.13, Mac Pro 2 x 2.26 Quad Core Intel Xeon, 16 gb Ram, Digi 003, Eleven Rack, Mackie 824 MK2 Monitors on Primacoustic pads, Focal Home Theatre 5.1 reference