7i96s - Looking for a few good inputs

Below is the rough wiring diagram for my installation of a 7i96s on a Boss3 Bridgeport mill retrofit.
The box on the lower right is the BP's control panel.  Spindle direction on top, Start and Hold switches on the bottom, and Emergency Stop on the right.  I've also got it wired up to the Z limit switches so far.  All NC switches, so I'm pretty sure I need to apply +5V to IN COMMON.
First, can I gang the Alarm circuit for the CL86T driver boards into one input.  All I need is a motor alarm.  Right?  Regardless of which axis is alarming, the program needs to stop.  Is that electrically possible?
Assuming that is possible, it frees up two inputs for the limit switches on another axis.  I don't have trip pins on X and Y just travel limits.  Are there other connections on the 7i96s that I can trick into being inputs?

 

You can common the drive fault outputs (by paralleling them)

Note: for mechanical limit switches you are better off using
12 or 24V for the switch power.

With mechanical switches the 7I96S input common can be
either + voltage or GND. If the input common is at +V,
the switch common would be GND. If the input common is GND,
the switch common must be +V.

If you need more inputs, there are a number of options:

1. Add a inexpensive parallel port breakout board to P1

2. Add a 7I84 or 7I84D (or 7I70 if you want a lot of inputs)

3. If you have a front panel, connect its I/O with a 7I73 to free up 7I96S
isolated inputs.

You can free up two inputs by eliminating the Z+ and Z- inputs.  Just run a single home switch and LCNC's soft-limits will take care of the rest.

I used to have a Z- on my mill, but then I realized there wasn't much point: the tool would have buried itself in a part or table before the ballscrew reached end of travel.

I'd like to go 24V, but I don't have room in the box to add another supply or another board. That's why I'm looking to milk the 7i96s for the last limit switches.
Given what @spumco just said, I can daisy chain the limit switches. Putting the driver board alarms in parallel frees up two inputs. One for X limits, and one for Y.
I want to keep the limit switches on the Z. This machine has a mechanical issue where if you go past the travel limit, the ball nut will wedge itself onto the column so tight that it requires a disassembly to free up.
Thank you, guys.

You can use stand-offs to double-stack Mesa boards.  It's not super-convenient to get at the bottom layer terminals, but it can be done.

Note: not all the mounting holes line up between various boards, but a 3D printer can get things sorted with some offset stand-offs.

Once you go double-stack, you've got an opportunity for a bunch more inputs with a smart serial daughterboard like PCW mentioned.

Oh, and if it were my retrofit, I'd duct-tape a 24v power supply to the outside of the enclosure before I used 5v for limits and other noise-sensitive components.

I was able to squeeze a 24V supply in. And with ganging the limit switches for X and then Y, and then ganging the alarms from the drivers, I got everything connected and have one input left over.