"open a pop-up window" message appeares at hideen tab.

Our site is Open a new tab in safari as following example.

---------------------- ----------------------- -----------------------

| Parent screen | → | Child screen_A | → |Child screen_B | 

---------------------- ----------------------- -----------------------


The timing when “This site is attempting to open a pop-up window”message appears is


iPad with OS10.

---------------------- ----------------------- -----------------------

| Parent screen | → | Child screen_A | → |Child screen_B | 

---------------------- ----------------------- -----------------------

↑ ↑

message - allow message - allow

          

iPad with OS11.

---------------------- ----------------------- -----------------------

| Parent screen | → | Child screen_A | → |Child screen_B | 

---------------------- ----------------------- -----------------------

message - allow

       ↑   

message - allow

User cannot allow while on Chlid screen_A tab. Tab transition to Parent screen is required.


Please tell me the way for To avoid "This site is attempting to open a pop-up window" message.

Or the way for to appears this message visible tab.