kyleml430

Currently working on replacing Intake Manifold. Fuel rail had to come out, and I know it's a good idea to replace the fuel injector seals. AutoZone gave me 16 o-rings for 8 injectors, and Mercedes dealership confirmed that the 8 fuel injectors require 16 o-rings. The 3 pictures below show what the injectors look like now that each of them have 1 new seal replaced (used grease to slide them on). However, I noticed that there were only 1 seal per fuel injector when I removed them. 2 fuel injectors will not fit below the orange plastic tab.

My main question is regarding these orange tabs above the o-rings. 3 fuel injectors had these tiny little plastic orange tabs completely break off while sliding the old o-rings off/sliding the new o-rings on. Are these orange tabs necessary? If so, does anyone know where I can buy them separately? The Mercedes dealership was just as curious as I am regarding this. Their catalog does not display this part separately (new fuel injectors are $135 a piece at the dealership, which is obviously a no-go - and I'm not interested in buying after-market fuel injectors either, as these work perfectly fine). 1 picture shows the orange tab fully on an injector, 1 picture shows the orange tab partially on the fuel injector, and 1 picture shows the orange tab completely off the fuel injector.

To re-state my questions:
Does each of the 8 fuel injectors require 1 o-ring or 2 o-rings each? If 2, how do they get put on? (they came out of the intake with only 1 o-ring on each)
Are these plastic orange (very brittle) tabs above the o-ring necessary? If so, is it possible and where can I get them separately?

Thank you!