Domodossola to MXP

It appears the best option to get from Domodossola (coming from Murren) to MXP will be Train to Gattinale then bus to MXP? Trenitalia site wants me to go to Milano Centrale then to MXP

That's because Trenitalia doesn't have the bus in it's database. I would go for the bus.
There are no night trains from Switzeland to Italy. You can look up train times on the Swiss Railways site: https://www.sbb.ch/en/

I currently have tickets for Domo to Murren via Brig, Lotchberg, Spiez, Interlaken Ost that I bought on SBB. The time for the ticket is 1248. My trip is starting in Milano Centrale. Id prefer to leave Milano Centrale at 12:23

What ticket have you got from Milan to Domodossola?
What ticket have you got from Domodossola to Mürren? Is it a Sparschein (saver) or a normal ticket?
The deal is that your Italian ticket (from Milan to Domodossola) will be for a specific train, and you must travel on that train. The train will be listed on the ticket.
You Swiss ticket (Domodossola to Mürren), if it is a normal ticket (cost CHF 75), it is not for a specific train, and you can travel on any train that day. But, if it is a saver ticket it is only valid on the train listed on the ticket.

Board a regional train from Domodossola to Gallarate and take a taxi from Gallarate station to MXP (the airport should be just a few minutes driving from the station).

My Swiss ticket is a normal ticket, which cost 75, but half that with my half fare card. So if I'm correct in interpreting you, I can buy any ticket from Milan to Domo, arriving at anytime regardless of whether I need to connect at Domo or continue through on same train, and my current ticket in Switzerland will be good for any time that day? I read elsewhere it is not recommended to connect in Domo. Thanks!

Can you just clarify something. " Flying back to states at 10:55 that morning" so you need to be a checkin around 07:30-08:00? This will require an overnight either at the airport or somewhere close, even central Milan would be pushing it.

As for Gattinale, I assume you mean Gallarate. There are train every couple of hours direct to MXP and the bus runs roughly hourly http://www.muoversi.regione.lombardia.it/planner/ReadFileEdmaServlet?idEdma=88958678&codiceLinea=GA-CAS

Yes, my flight is out of Milan and I have two rooms at the Sheraton at MXP for the night before the flight. Was just seeing if there was an option to leave late from Murren and arrive at MXP a couple hours prior to flight. It's my family of four.

Family of 4 ! Forget the bus, get a taxi from Gallarate station direct to the hotel.

My Swiss ticket is a normal ticket, which cost 75, but half that with my half fare card. So if I'm correct in interpreting you, I can buy any ticket from Milan to Domo, arriving at anytime regardless of whether I need to connect at Domo or continue through on same train, and my current ticket in Switzerland will be good for any time that day?

Correct, but your ticket from Milano to Domodossola will be specific to one train.

I read elsewhere it is not recommended to connect in Domo.

I am not sure why not, apart from the fact it is unnecessary as many trains run direct from Milano to Switzerland, they just stop at Domodossola and change crews there. Event if you have two tickets (Milano to Domodossola and Domodossola to Mürren), you do not need to get off the train.**

Thanks all. I was examining the train schedules and I see my best two options from Milan do go straight to Spiez or Brig without changing trains. Think I know I can use either of these trains and be good. Thanks!!

One more question for you. You did buy Half Fare Cards for everyone in your family correct?

You will be traveling from Muerren to Gallarate on Monday August 21. staying overnight at the MXP Sheration. Then flying back to NYC on August 22.

The latest good time to leave Muerren is 17:28. You will take the train to Gruetschalp, then the lift down to Lauterbrunnen and get the train to Interlaken Ost and connect to a train to Spiez, then connect to an EC train that will go direct to Gallarate, arriving at 21:03. Taxi to the Sheraton from there. The EC train has required reservations from Domodossola to Gallarate.

The connection time in Interlaken Ost is only 6 minutes. If you are worried about that, you can leave Muerren at 16:58 and you will have 36 minutes at Interlaken Ost. Since you would have reservations on the EC train you get from Spiez, it is important that you make that train. You can do that because the Swiss trains up to Spiez allow you to take any train to Spiez.

Wow! Thank you so much for looking at my schedule so closely! I haven't thought much about the return except to see if there were night trains, which I didn't think would be practical due to so many changes. Your advice is excellent! And it doesn't seem like a bad trip back either. 4 hours ish.

Stayed in Gallarate last month when I landed in the evening. From the airport to the city center of Gallarate is less than 15 min drive. A taxi will be just as fast. There is a bus also, but I'm sure it takes a bit longer. If it's a few of you with luggage I would go for the taxi. I'm sure it's no more than 25-30€

Roberto, I like your style! I'm going to check prices beforehand. If all my money isn't gone after Switzerland we will take a cab for sure!