Connect 3rd N3048 switch into existing stack

hello,

I have one stack  ( 2 x N3048 ) . This stack is connected to another stack ( 2 x Force 10 S3048-ON ) 

Now, I need to buy and connect an additional N3048 . It will be connected in the same N3048 stack.

How should I re-cable the uplink between the new ( 3 x N3048 ) stack and  Force 10 stack ? 

This is how the current cabling look like. 

S3048-ON is using all 4 x QSFP ports ( 2 for stacking and 2 for uplink )