The best way to level all of the Syndicates at once is to finish your current Priority contract, then at Daily Reset, switch allegiances. You will now get 50% bonuses to contracts from that faction and additional Dark Matter Ingots. Then do whatever you can to work on all 3 faction bounties at once during one event. Tomorrow, do the same thing. The only progress you will ever lose if the Priority contracts you currently have are not finished.

No you can bounce weekly between them. You can also go turn your credits into other syndicates boxes to increase their levels when not associated with them that week.

[quote]Does any progress made with other syndicates reset if I change my allegiance or do I retain my standing with them all?[/quote] Mine remained unchanged! First with Cabal…now with Fallen… The only thing is the initial ‘apply to join’ mission reappears, ie, drop x amount of ingots / do a contested run. Also, twice now, I’ve purchased the sword grip upgrade - clearly signed, only to find I’ve just bought another unwanted gun. That tabletop display is glitchy, it seems…😵‍💫 Cheers! 🖖👻