Dominant 15 month boxer

Question
I have 2 gorgeous female 15 month old boxers (sisters).  They have completely different natures, Maisie has had her season and is very lively, gets really excited, jumps up on us/other people and is starting to get more aggressive in play with her sister.  My other boxer Kim hasn't had her season yet, is quite quiet and mature and does what she's told but eats everything, pens, coal you name it if it's lying around she'll chew it!  There are a few things I'm concerned about (1) Kim eating everything, (2) Kim not having had her season yet (3) Maisie starting to get more aggressive with Kim.  More worryingly Maisie showed a bit of aggression towards my mum's neighbours teenager.  We were standing at my mum's door and I'm not sure if she was protecting us or what but this is out of character for her.  The two of them do bark at people/dogs but are very friendly when people come over to them (too friendly!!).  I would like to breed both of them at some point but wonder what will calm Maisie down.  Sorry lots of questions there but would appreciate your advice.  Thanks, Natalie

Answer
1) One is the Alpha... and obviously Maisie is the Alpha between the two so don't worry about that, as Kim is the Omega (last in the chain) and accepts it

2) Reprimand Maisie when she is too aggressive toward Kim, do not allow her to dominate to the point of abusive

3) Seasons are being in "heat" and differ for animals (dogs) as it differs for us. Some earlier and some later. Do not worry about that either as Kim will when her body wants.

4) Do not breed either until they are at minimum 2 years old. Period!

5) Do not allow Maisie to be aggressive to other people. Chastise her, reprimand her, get a hold of that problem and be consistent with the reprimanding.

6)Nothing will "calm" Maisie down except you. You must work with her on the type of behavior you will accept. She is a livelier Boxer, higher strung, and dominate. You must be consistent with your training and allowing the good behavior, chastising the bad unacceptable behavior. Reward her with a "special" treat that you normally do not give, for her  good behavior, as when you tell her "no" or whatever terms you use (but be consistent with it) for aggression toward people, or toward Kim, give her a treat when she minds you. She will associate good behavior and treat-reward, to bad behavior reprimanding and no treat.