Add usercontrol to placeholder dynamically in content page

Question

I have a content page with two hyperlinks A and B and a placeholder. If hyperlink A is clicked add A.ascx and if hyperlink B is clicked add B.ascx to the placeholder. Both A.ascx and B.ascx have a textbox and an Add button to add data to SQL tables. (A.ascx updates TableA and B.ascx updates TableB)

I am facing below problem

When content page loads and the page have only two hyperlinks A and B. I click on hyperlink A then A.ascx gets added to placeholder. I enter value in textbox and click on Add button. The database is successfully updated.

Next I click on hyperlink B then B.ascx gets added to placeholder. I enter value in textbox and click on Add button. The Add event is not getting called and the value in textbox is getting cleared. If I re-enter the same value in textbox and click on Add button again then the data is getting saved.

Can you please help me in fixing the problem?

Thanks.