Any workaround for making a 4-layer PCB in Fritzing?

Hello Fritzing Community,

I was wondering if anyone had any advice as to a potential workaround to create a 4-layer PCB in Fritzing?

I've made several 2-layer PCBs and I would now like to attempt to create a single board, featuring all these circuits and use 2 internal layers to form connections between the vias/headers as there isn't enough available space on the outer layers.

Since you can't explicitly create a 4-layer PCB in the software, is there a way in which I could create two sets of Gerber files (outer layers and inner layers) and then edit/combine them so that they would technically be a 4-layer PCB (as far as production is concerned)?

Any advice and information would be greatly appreciated - I really don't want to have to draw up 10 circuits again in another package. Image may be NSFW.
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Thanks. Image may be NSFW.
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Kind Regards,
A.K