Marx and Lionel accessory compatibility

Before I get into the nature of my question or problem, I need to make it clear that I am a newcomer to Marx toy train and accessory operations. I have always been a Lionel collector and operator and I have found in my infancy of Marx collecting and operating subtle differences between the two manufacturers.

I recently decided to build a special Christmas layout with the intent of being simple to take down at some point in the new year as this layout is in my apartment and I will be moving out in March. Let's call it a Christmas layout, that's really what it is as I could never develop a truly permanent layout in the apartment.

I have two Lionel number 394 rotary beacons, two Lionel lamp posts, two Marx two lamp flood lights, and one Marx One lamp flood light running to the accessory terminal of my transformer. I have the Rotary beacons and the Marx flood lights on one series circuit and the lamp posts and a modified Mark's railroad crossing post or a previous owner added a light to the pole on its own series circuit. For reasons I don't understand every time a Mark's floodlight post is connected into the circuit the marks accessories seem to draw more power then the Lionel and the power in the circuit diminishes after every Mark's accessory significantly. I do not find the discourse as noticeably when the Lionel accessories are the only accessories operating on the circuit. What is it that I am not doing right? I have been puzzling over this for days and I've had to rewire more than once and have not been able to correct the problem. I've decided today that I'm going to separate the Marx accessories into their own series circuit from the Lionel and see if that makes the difference.

Can anyone with experience with Marx provide an insight to help me?

Realized after I wrote the above I wrote series circuit and intended parallel circuit.