Electronic – Efficacy of more lines of power on legacy ribbon connector with limitations

A conundrum. I've been asked if I can add more current capacity and less voltage drop to a legacy connector, but I have limitations. For the legacy products to work on this same connector it needs to keep the 10pin pinout order the same. This allows a 14pin ribbon cable to simply cut off it's unused pins for those products. But they'd like new products that might draw more current. It's a modular system, so there are unknowns about how much current each module needs. Some modules will draw around 30mA per 3.3v, 5v, +15v, and -15v as were used with this connector. But some modules draw up to 110mA. (For power hungry ones that draw 200mA, there is a beefier power option.) The ribbon cable in question is about 12 inches long and it's 1mm pitch 28AWG (with a 2mm IDC connector on each each end.)
I'd like to consider a whole new pinout, but since this pinout already parallels the power signals in this order -15v Ground +15v +5 +3.3v in that order, perhaps another 4 pins of -15v +15v +5 +3.3v in that order will work OK. I'd rather intersperse ground between signals but they want to only go to 14pins if possible. Should I bother? Perhaps they can simply double up on the connectors for certain modules. The only issue if done that way is that the Clock and Data lines end up with more "stubs" or parallel connections and so more potential for reflections (unless we cut those signal off those secondary cables.) Plus using two power connectors seems a little odd. Schematically it's like this. (P.S. Yes it's got a digital ground for +3.3v and 5v, and an analog ground for audio and +/-15v.)