Quote ="Abe Froman"By my understanding you can only have 1 club or federation trained marquee, but I may be getting that wrong ?'"
Not quite; a club can have three marquees, one of which needs to be federation trained (or homegrown). So a team can have 3 homegrown marquees (for a cap total of 150k), 1 federation trained marquee, and 2 non-fed marquees (for a cap total of 400k), 2 non-fed marquees (for a cap total of 300k), but a team cannot have 3 non-fed trained marquees.
For a real life example, Warrington could have Williams (Federation trained), Nathan Cleary (Non-Fed Trained) and James Tedesco (Non-Fed Trained) as 3 marquees for a total of 400k cap space. However, they could not then do a swap deal switching Williams for Addo-Carr, as that would take their fed trained marquee out for another non-fed trained marquee, even if they had an additional 50k cap space (as 3x non-fed marquee players would be 450k).