How can I add selectable additional options to a main item in a cart?

[KakNaZlo]

Hello, everyone!
I think someone has already encountered something like this
I need to add the ability to select additional options for an item that will go into the cart along with the main item.
For example
User goes to t-shirt page, there he can choose two additional items. Let it be a patch. The user can choose the material of each patch and color accordingly.

Tried to do it with variants, but then the main item changes. This is not what I need.
Does anyone know how this can be implemented without using additional plugins?
I would be grateful for advice.

[Uhrick]

hey, KakNazio, good morning.

I'm afraid that this would require some theme coding or shopify app. From what I know, shopify doesn't have natively this kind of option to make another product be added to a cart from a first product page. 

[KakNaZlo]

Thanks for the reply!
I already understood that it is necessary to write a solution for my problem, I just can't figure out how to do it
I originally thought of doing it with product variants, but when you change the variant, the item changes globally, not added along with the main item to the cart

[Uhrick]

Oh, sorry, what I mean is that it's complex work, and I'm not sure people on the forum will be able to assist you with a quick fix. I believe that, for this to work, you'll need to use the shopify cart api reference to add your extra product, this is the direction that I can send for you to try to achieve the solution, but feel free to dm or email me if you think you'll need professional assistance.