Hello Geayofout60
There is no need for dividing your ticket.
You purchase an Arcobaleno Transfrontaliera return ticket after arrival, from Malpensa T1 to Chironico. Then you travel on the RE train from Malpensa to Lugano. As soon as you cross the IT/CH border, your transfrontaliera ticket turns into an Arcobaleno Day Pass that can be used for the remainder of the day, until 5 AM the next day on public transport on Ticino territory; consequently, you can take a stop at Lugano and continue later with the same ticket. The four hours limitation applies for the Italian stretch only.
In theory, you could purchase the ticket ahead of time, hoping the flight will be on time and you will make the transfer to the border within these 4 hours.
https://arcobaleno.ch/en/home/tickets/cross-border-tickets
Does that make sense?
Ps. If you think it is overpriced, you have to split the journeys, and purchase a single ride ticket for Lugano-Chironico upon baggage check-in at Lugano station. You can purchase the ticket and do baggage check-in at the same counter. Simply tell the agent at what time you want to continue from Lugano to Chironico.
Kind regards,
Roland