would you want to lock the selection or Would they be able to switch their selection eg. if someone selects session 1 session2 3 grey out and they cant switch to a different option. if not then you can just use the single answer multiple choice question with radio buttons

@agabdulaziz - You can use JavaScript to disable the checkbox button associated with Session 3 when Session 1 is selected. It seems like this would become very complicated, very quickly. Every time something is selected or deselected you’ll have to check for conflicts or lack of conflicts across all choices.

Hi @agabdulaziz, I am assuming that by grayed out you meant to say only to change the color of options which are not selected and not disabling them for selection. 

Please review this link for details.

Thanks,

JB