Changing single electrical switch to dual switch-outlet: How to connect neutral wire?

Question

I want to change my single switch to a dual switch-outlet. The instructions seem simple enough, but the current wiring doesn't match anything I've found in home wiring books.

There are three wires coming into the box: one is to the light fixture, the other two unknown.

Dashed lines are neutral

There is power on the black wires tied together. The black wire from the switch to the light is (obviously) dead until the switch is on.

The new switch-outlet combo has to be connected to neutral.

There are three neutral wires in the box, one of which definitely goes to the light fixture.

It seems that I just need to connect a neutral wire from the new switch-outlet to the group of wires already twisted together. I don't see any other way to do it, but want to be 100% sure before I do anything.

Original image links:
https://drive.google.com/file/d/1iv0pGPqF99K_HI_Os7NYei3A7KWTVgNz/view?usp=share_link
https://drive.google.com/file/d/1jPUhcRX970GkTe0JnHIQV0J1j7Wu7fOS/view?usp=share_link
https://drive.google.com/file/d/1NUvYwhlWZaK6WJ4SGP9jQr76pI5BdlcS/view?usp=share_link

Answer 1

You have it right, might need the next size wire nut up, but unsure.

Use a piece of white wire from the nut to the new switch.

One cable coming in is the power, the second cable goes probably to an outlet, and the third is for the light.

Turn off the power at the breaker and double check no power is on when touching the wires.

The new wire nut should be able to take 4 wires of that gauge. I think they look 14 gauge, but might be 12 gauge. Gauge number will be on the outside of the cable covering.