link idea to product line Merged

Some ideas are relevant to multiple similar products in a product line. 

For example, if there was a product line called "mobile apps" with individual products for IOS and Android, you'd probably link "continue working offline" to the product line since it's pertinent to both products.  You could make the same argument about a feature for a line of bicycles.
It would be promoted to a feature on one or more selected products in the line potentially at different times.