Split cart lines into ordinary lines and option groups, for rendering: show a group as one block (its sizes, then its charges under them) and let the quantity be edited on the group only. Order is kept: a group sits where its first line is.
Split cart lines into ordinary lines and option groups, for rendering: show a group as one block (its sizes, then its charges under them) and let the quantity be edited on the group only. Order is kept: a group sits where its first line is.