Okay...
I believe that if I have understood you and I still think that it can work ...
In the video I have uploaded, the dialog line "hello" has a value of -1 to be displayed. When you use it, change the value to -2 and it disappears. When he speaks again, you set the value to -1 in "actions" so that it will be shown again.
You do not have to leave the option to delete the dialogue part entry checked
Hopefully we're talking about the same ... hahahaha
Good luck!
A greeting!