Yes, the Chapter 13 can be admended anytime there is a change in the income. But they will have to be notifed as soon as possible.
But depending on the state you live in, matters as to the debt situation, in some states husbands and wife's share debts in common by virture of being married.
The attorney that did your chapter 13 filing for you, needs to look at this,
And no the chapter 13 do not garnish any pay, if you fail to pay and if you don't notify the court, they will just let the chapter 13 go into defaut and your plan will be droped ( disqualified) so that the debtors will be able to come back after you.
But your bankrupcy attorney will be able to tell you if you need to change this over to a chapter 7 perhaps or if you need to re-file under your name only.