Access a control inside an usercontrol from another control inside another usercontrol

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Hi.
Think the following scenario.
UC1 with a textbox control and a button control.
UC2 with a textbox control and a button control too.

I need to, on the click event of the button inside the UC1, give a value to
the textbox inside the UC2.

In the real scenario I will have a lot of UC2, one accessing another.

Anyone knows the best way to do that?

Thanks

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