canasta melds

Not if you're playing for money.

And if you're not?

By consensus of all playing - understanding that this is an occasional concession made to age, inebriation, yips or youth and is a well better not dipped into too often.

I have a question (and I can't figure out how to start a new post)- 3 of us are playing with out partners, can I add to a meld I have already laid down before. For example if I put down 3 Seven's and a wild card and my turn has come around a few times and I now have more sevens can I add 2 more to my meld?

You can only have a natural 7 canasta