That’s not how you setup options for castsequence macros and you also need to include existence checks for mouseover condition sets. https://wow.gamepedia.com/MACRO_castsequence
That said, this is a terrible idea, please don’t do it. You’ll be much better off using modifier macros where you have more control.
i got all my heals on mouseover keybound and i just spam that shty, it’s 3 keys easy to do, i was just thinking to improve efficiency i could marcro it all together LOLHEALHOTSPAMFTF :