Can a bi-polar person be considered a co-dependent?
Yes, a codependent person can be bi-polar. I believe they are related problems.
My theory is that the Super-responsible person who comes out of a Parental Inversion family system has suppression fo the Inner child which causes a life of depression. It also leads into all kind of ‘codependent’ type relationships.
The personality system that keeps the Inner Child bottled up sometimes breaks down and the Inner child breaks out and does stuff it has been prevented from doing. There are now no controls on the Inner Child and the result may feel pleasant but end up disastrous.
That is, I believe, how bi-polar gets set up.

​Can a person with avoidant personality disorder have a wife and children?
Yes they can.
The avoidant male or female is somewhat an expert at being peaceful and looking very calm and together. If their partner is not sensitive to the lack of personal sharing in the relationship, then it is quite possible for an avoidant person to end up married and with children.
The Avoidant Personality creates the persona that accomplishes their life purpose to look like they are living when they are just going through the motions. The Avoidant woman looks like the perfect wife by doing everything by the book, following rules, robotic-like. Think of the Stepford wives.
For the Avoidant to avoid risk it is advantageous to be married and have children. It is a safe place to hide. No one can demand that they change. No one thinks there is anything wrong. They are, after all intensely, focused on keeping up appearances and, therefore, looking the part.
Only if their spouse needs intimacy will ther be a problem - a growing dissatisfaction. There is sex without bonding, conversations without sharing, live without real connection. The marital connection, the holy bond, gradually withers away through neglect and so do the two marital partners.
The resultant relationship lacks real love. Is not life-giving. Is not emotionally healthy. But looks like the perfect marriage. Imagine the possibilities for gas-lighting. If you are married to the Avoidant spouse you will never be able to explain to them or to others why you are deeply dissatisfied with the marriage.
Confront your partner? That never happens with an avoidant spouse.
You may not even be clear in your own mind what is wrong. You do not realize that the most basic ingredient in a true godly marriage is missing - the connection, bonding, unity. You may not understand why you are sick and dying. Love maintains the human spirit - our core being. Our core being maintains the health of our body. When the spirit languishes for lack of love so will the body. 
How do you explain to someone outside the marriage that you can never talk about anything of  personal significance with you partner? You can't. No one understands. It is very difficult to explain to your friends and allies what is wrong unless they discern it themselves.