After new variants have been added to a product, these variants can be products that have already been assigned.
You have created a new variant in the production level. This article was previously already assigned to a shop and you now want the new variant into the shop.
Go to this in the shop administration under "Catalog -> Products -> [your product] -> edit". A yellow button "synchronize" appears in the right information box.
On the following page you can then select all variants that are available in the shop. all the available data can be transferred, but only part of the available data can be transferred. variants.
If you do not see a yellow button for the product, there are no new variants, that you can take over.