hi i'm creating a shirt site for my client. now i have the following problem: the attributes of the shirts are as follows: fit, size, collar, cuffs. they are all single-level attributes. the problem that the client has posed is that he would need an additional attribute: the collection. but for one type of collection there should be a large set and then one or more subsets. but with magento it is not possible to set attribute and then sub attributes. how can this problem be solved?