It is well settled, as held by Hon'ble Supreme Court in Vanamala Vs. H.M. Ranganatha Bhatta 1995(5) SCC 299, that a wife who obtains divorce by mutual consent cannot be denied maintenance by virtue of section 125 (4) of the code. If the marriage between the parties is terminated by a decree of consent divorce, that would not amount to live separately by mutual consent. The claim of maintenance under section 125 of the code by a divorced wife is based on the foundation provided under explanation (b) to sub-section (1) of section 125 of the code. If the divorced wife is unable to maintain herself, and if she has not re-married, she jwill be entitled to claim maintenance allowance. A woman after divorce became a destitute. If she is not able to maintain herself and remain unmarried, the man who was once her husband continues to be under a statutory duty and obligation to provide maintenance to her.
In the judgement, the maintenance of Rs.500/- per month was provided to the wife, as that was the ceiling at that time. Later on the provision has been amended and now there is no ceiling. you are, therefore, entitled to the amount prevailing in these days.
Comparing to his annual income, the maintenance he is providing to your child is pea nuts. You have to file application under Section 125 for yourself and as well as for your child. The total amount of monthly maintenance for both of you comes to about 1/3rd of his monthly earnings. While calculating his monthly earnings, his statutory deductions and necessary load deductions will be taken into consideration and not sister's marriage liability. The quantum of interim relief depends upon the documentary evidence you can place on record about his monthly/yearly earnings.