In Interest of JM and GM

OPINION

KLINGEMAN, Justice.

This is an appeal from an Order to Modify in Suit Affecting the Parent-Child Relationship. A decree of divorce was entered between R.M. and L.M., the parents of the subject children, on September 3, 1976, wherein R.M., their father, was ordered to pay child support for his and L.M.’s two minor children, in the following amounts:

September 15,1976-January 1,1977

$250 per month per child, or $500 per month;

January 1,1977-June 1,1977

$375 per month per child, or $750 per month;

June 1,1977-January 1,1978

$500 per month per child, or $1,000 per month;

January 1,1978-June 1,1978