Every time I visit home, Mom bugs me about having kids. So, for my next visit, I’m going to use Rent-A- Relative, a service that supplies stand-ins for all family events — they even offer toddlers. Can’t make that wedding? Send a look-alike. Can’t bear your niece’s violin concerts? Send in the clone. And if you’re looking to make a bit of extra cash, apply to be a relative for someone else (they’re looking for biker types in Boston). If you’ve seen the TV ads for this pseudo-company, you know it’s the alter business ego of Webmiles, an outfit that lets you earn frequent-flier miles for shopping online — and the site would be a lot funnier if it didn’t remind you of that quite so often.