Shortcut to provide generated password with current password by Keychain?

I need help with providing old password together with generated password because both are required even though I have already login.
my problem is when Keychain pop up during password reset, Keychain provides existing password instead of auto filling existing and generated passwords.
What I remember doing to avoid Keychain provide existing password is to change password by switching from App Dialogue Box to Keychain after I login to change password; this created Problem that old password is no longer available.
I preferred Keychain over Apps due to security concerns.