+5V reference, Signal Ground - Multiple splice points acceptable?

Hello!

I am currently laying out my system design for a tinkering project.

I am adding a link G5 neo 4 to inside the cabin where it needs to interface with a few in-cabin components, or components from the factory harness.

The factory harness located the stock ECU in the engine bay, so I have pulled those wires back through the firewall.

However I wish to add a firewall (or near it) bulkhead connector for a few reasons.

1: allow for the engine itself to be a sub-harness.

2: land my spare ECU pins at this mid-connection for future expansion.

But in doing this it begs a few practicality questions.

I wish to use DT Bus connectors to multiplex these circuits as I have quite a few sensors that need these signals, and it would be nice to have a serviceable junction on the engine side of the firewall (and to not pass all of those signals through multiple pins on the mid-harness connector)

1: Is it kosher to combine the non-shielded signal grounds and +5V reference on the engine side of a mid-harness connector?

2: Is it acceptable to then have another splice point next to the ECU connection to join the single, larger conductor from the mid-harness break to the other signals inside of the factory harness and to the ECU? (and join in the shielded connections)?

I currently need to make 12 sensor ground connections and about 8 +5V reference connections. Not a huge amount, but with 1/4 of them being inside the firewall it would take up quite a few pins at the mid harness connector to pass them through.

I do realize it adds more connection spots, and for strict simplicity and cost this would not be the way to do it, but given the nature of my very cramped engine bay and cabin, I would prefer a sub-harness methodology.

Yes, you'll be fine having a couple points where the 5V and sensor ground split off.

The biggest thing to do is make sure you have quality crimps/splices, to ensure the lowest resistance in the circuit possible, and good sealed connectors for reliability.