About subsidiary view
I want to use Subsidiary view.
In Subsidiary view, we can watch only 1 Lineitem not several Lineitems.
I want Enduser to input the data in these Lineitems in one Dashboard.
Should I have to make a another module?
Definitely make another module with the correct lists for that input line item. Then reference the input line item in the main module.
There are a couple of valid reasons for building subsidiary view, one of them is for an output module where you need it as a filter for reporting purposes. But in your case, as an input, it is strongly recommended that you have that line item in a separate module - you can also learn more about in the Planual and as part of the PLANS methodology.1
There are only 5 exceptions given by Planual in order for us to create Subsidiary views. Read more here
2.01-06 Avoid Using Subsidiary Views - Anaplan Community
Yours does not qualify for any exception. As @JaredDolich mentioned create another module for it.
Hope that helps