How can I set a specific conditional function in time domain

Hi all, would anyone help me about one question of the conditional setting of a time domain function? I have two function y1 and y2, whose slew rate can be defined independently. I want to set a condition of y2, by setting "when y2 and y3 meet between t1 and t2, y2 must follow y1".

Attached is the worksheet, would anyone teach me how to do it?

Thank you!