Mark Molden, chief executive of Care for the Family, said the charity was likely to make "one or two" of Positive Parenting's 14 staff redundant when it transferred some of Positive Parenting's back-office functions to its own head office in Cardiff.
Molden said one of Positive Parenting's six trustees would join the Care for the Family board, but the others would stand down.
He said Care for the Family would keep Positive Parenting's Birmingham head office and four regional offices open, and would continue to run its parenting courses using its existing name and branding.
Molden told Third Sector the move was not a result of financial pressures and both charities were in good financial health. Ken Shorey, chief executive of Positive Parenting, is due to retire in 2010 and will stay on in an advisory role at the new charity during the transition, said Molden.
"The charities have similar aims and ethos in supporting parents in the ups and downs of family life," he added. "This move will enable more parents to access the charities' complementary resources and delivery models, meaning more parents can find help, advice and support."