The plus sign that’s part of the Rite Aid wellness+ loyalty program is an apt symbol. The program, launched nationally eight months ago, already has 29 million members, having added seven million members in the past three months alone. The program’s growth is good news for the drugstore retailer: members’ market baskets are 50% larger than those of non-members, and these members are now accounting for 70% of front-end sales, according to Rite Aid president and CEO John Standley. The wellness+ program....