Windows 7: How to always pop up login dialog to login as User other than current

Hi folks

I have numerous PCs all running Windows 7.Home.32 bit in LAN peer2peer Group with shared folders.
Shared folders are effected at the security and sharing tabs.
All PC has Users with password, some User (name & password) are the same in these PCs.

Lets assume the following nomenclature:
PC1.SFd_All: Shared folder in PC1 accessible for All Users named in PC1
PC1.SFd_1A: Shared folder in PC1 accessible for one User only, namely User_1A
User_1&2: User registered in PC1 & PC2
User_1: User registered only in PC1
User_2: User registered only in PC2

These are some events in my tinkering:
E1. User_2 log in in PC2. User_2 clicks on PC1.SFd_All via the network group; login dialog pops up asking for username & password. User_2 log in as User_1&2 (with password) to access.
E2. User_2 from PC2 next clicks on PC1.SFd_1A, error message "..check with admin..". appears instead of poping up the login dialog.

If step E2 is done before E1, login dialog will appear allowing User_2 to log as User_1A. Thus my question



What can be done at PC1 or PC2 (or both) to always have "login dialog" to pop up so that i can access a shared folder with another user name & password (other than current user)?

Sorry for the messy first question at this forum. Thousand apologies!!