How to make products only available when purchased with another?

[notrabnai]

Hey Looked for the answer but couldn't find a solution that worked for me. I feel this would be pretty simple but basically, I wanna make it so certain products can only be purchased with another product. For example, I sell saunas and sauna heaters and the sauna heaters can only be purchased with a sauna. 

I wanna make it so that if someone tries to add the sauna heater to the cart it will say they need to order a sauna with it too and they can't purchase the sauna heater alone

I added some bundle apps but couldn't figure out how to get this to work.

Thanks!

[gr_trading]

This can be done using custom dev in theme.

We will provide option to mark group of products, then write script to validate the cart items.

Write the same script to validate on product pages if associated product is already in cart if not, will remove the option of buy now and checkout and display related msg and option to redirect or directly add items into cart.