Question on using pass in euro city

Hello everyone - we will be visiting switzerland from august 11th to august 17th - i have been struggling to make a decision on which pass to buy. we are 2 adults and 2 kids, am thinking of buying 1 day pass and cover the kids under it and 1 4 day pass - couple of days we will buy tickets as and when required - does this make sense?

Also we will enter into switzerland from milan on 11th, can i do the following?

1 ticket from milan to lucern through arth, 1 ticket to chiasso - so 1 adult and 2 kids will travel on the pass from chiasso - both using eurocity 16? since 1 ticket am booking directly on trenitalia, i can choose the ticket but what about the other adult and 2 kids - how do i reserve seats for them as they will be travelling on the pass from chiasso? Is this even possible or am i complicating this?

any help/advise would be appreciated.

Hi anicraj, welcome to MySwissAlps!

I am not sure I understand your plans. Which exact passes do you mean? Swiss Travel Pass? Swiss Travel Pass Flex perhaps? Why would you buy different passes for both adults? What do you travel plans look like, day trips included?

I think you are trying to find a solution that's too complicated, but perhaps it makes sense if you provide some additional information.

Thanks!