Dynamic connection in the package control flow

I am using SSIS 2016

. I created Package Part Control Flow

, as you can see in this image:

The subject of this Package Part Control Flow

is to have a loop for all files in one folder and move all files to another folder.

I have Foreach Loop Container

and File System Task

.

I created this variable

Then I created two Flat File Connection Manager

:

Now I need to configure expressions

for Connection String

for each Flat File Connection Manager

.

But as you can see, I have no access to my variables.

I need to set up the connection managers internally Package Parts Control Flow

and then in the package where I use this one Package Parts Control Flow

, I will pass the variable values.

The way I would like to send the value for the variables Package Parts Control Flow

.

Can I have an expression in the ConnectionString

Flat File Connection Manager

inside Package Parts Control Flow

using a variable?