The pass for Italy will only cover journeys in Italy. From Venice to Munich, it will only be valid up to the border between Italy and Austria (Brenner).

You would need a global pass, or buy an extra ticket from Brenner to Munich.

I doubt if a pass would be worth while but you can calculate yourself:

1. milan airport to milan: www.trenitalia.com
2. milan to como: www.trenitalia.com
3. como to venice: www.trenitalia.com
4. venice to munich: www.trenitalia.com or www.bahn.com or tickets.oebb.at (prices can be different on these websites).

It will also depend on WHAT treni you will use-the regionale are much more cheaper as the faster Frecce/or the private, also red, ITALO (not takes passes anyway). Being right now in IT and having done some of these-and tomorrow, hopefully, as again scioperta=strike announced, to MXP: passes also NOT valid to MXP-airport, have to pay till at last first normale stazione.

Al in all-and certainly if you preplan and book before, just as you likely will do with HTLs-just book advance/fixed, and to Como buy on the day-as its regional. Mil-Vnz can choose between TrenItalia/Frecce or Italo-or even use the hourly regionale veloce (change also Verona)-nice new doubledeckers by TreNord (used them a few hrs ago).

There are 2 passes for Italy - The Interrail one and one direct from Trenitalia. Although they are almost identical price of about 360 euro for 3 trips or 440 euro for 4 trips, there are 2 fundamental differences to factor in:

The Trenitalia pass allows travel on any Trenitalia train without reservation fees whereas Interrail requires a pre-paid reservation for express trains of 10 euro per person (3 euro for Intercity trains).

The Trenitalia pass allows 3 or 4 journeys in 7 days with no changes of train - i.e. each train journey counts as one of 3 (or 4). The Interrail pass allows 3 or 4 travel days in a month with unlimited trains in that 24 hours.

I tend to agree with the previous post that you will probably be better to cost the individual tickets for your group. Milan apt - Milan - Como - Venice is well under 100 euro pp, but the trip from Venice to Munich will probably cost in the order of 100 euro per person.

A Global pass which will cover your group for 4 days in a month will be 667 euro plus some reservations. This allows travel across Europe so includes the full journey you plan and is totally flexible (subject to getting reservations and fees)

The Eurail One Country Pass Italy is not valid on Malpensa Express trains between Milan Malpensa Airport and Milan. 

Also do look like others say before how much it would cost with normal tickets, and how with the Pass. Also, you could think to buy a Global Pass wich is valid in the Hole continent. 

Keep in mind that the long-distance trains Frecciarossa in Italy and Trenitalia Eurocity needs a reservation for 10€, local trains do not need a reservation. The Eurocity to Munich has only optional reservations, but you need to pay a supplement of 10€ in 2nd class. The reservation is for free if you book at a train station in Italy or online via Czech Railways. Online via Austrian Railways you pay extra 3€ for the reservation.