In reply to Stephen Horne - Rockfax:
That's not how it works. Gmail is "dot-blind" in that it ignores the dots when resolving email addresses, so justanexample@gmail.com, just.an.example@gmail.com and just.an.e.x.a.m.p.l.e@gmail.com will all go to the same mailbox. But you can't add arbitrary prefixes and expect the same thing to work. Otherwise mail for rod.smith, jane.smith and freddie.smith (and every other {firstname}.smith) would all end up in the inbox of whoever registered "smith" on its own.
So, while you could use dot patterns to create variations of your email address, remembering them might be tricky.
An easier way to do it (if you are using gmail) is to make use of its +suffix feature. (Caveat, I haven't actually used this for years, so test it first.) Just add "+" and some text after your regular email address, but before the @, and any messages will go to the primary email address. (So mail addressed to justanexample+child1@gmail.com and justanexample+child2@gmail.com will all get delivered to justanexample@gmail.com.)