Deborah Annette, just shy of 3 years old, has lived most of her short life in Barbara Bernhardt's Takoma Park home, and Bernhardt is the only mother she knows. But under a ruling yesterday by Maryland's Court of Special Appeals, Deborah could soon be removed from the home and returned to the custody of a Washington adoption agency.

That is the wish of a child welfare agency in Texas, where Deborah was born, which placed her for adoption through the Washington area agency. The problem, as the Texas welfare agency sees it, is that Berbhardt is divorced from her husband and Deborah's natural mother wanted the child to have a home with both a mother and a father.

Bernhardt won't give up Deborah without a big fight, her lawyer asserts.

The adoption agency, Lutheran Social Services of the National Capital Area, has charged in court that Bernhardt concealed the fact that she and her husband were separated when Deborah was placed in their home for a trial period in March 1976.

After learning in July 1976, of the separation, the agency reopened its investigation of the couple's "suitability" as adoptive parents and ultimately recommended that Deborah be removed from the home, according to the court decision.

Bernhardts attorney, Frank Kratovil, asserts that the agency "made an evaluation of he entire life and character based on that one fact - the separation. They not only blamed her totally for the marriage breakup, but for the concealment, and they punished her for her so-called deception."

To have the adoption made final, Bernhardt needed the consent of the agency in Dallas, Tex., where Deborah was born. That agency, the Dallas County Child Welfare Unit, had originally placed Deborah through Lutheran Services and still maintained jurisdiction over the child.

After receiving a report from Lutheran Services in October 1976, with the newly discovered fact that the Bernhardts were separated, the Dallas agency requested Deborab's immediate removal from the Bernhardt home "for the welfare of the child," according to yesterday's court opinion.

When Deborah was not returned to Lutheran Services, both agencies filed a petition in Montgomery County Circuit Court seeking custody, and Bernhardt responded with her own petition for both adoption and custody.

In the subsequent trial, a representative of the Texas agency testified that Deborah's natural mother wanted the child to have a home with both a mother and a father.

He testified that "to bring a child into a family that is dissolving . . . and put further stress on that family and stress on the child" would be improper, according to the appellate opinion.

During that trial, Bernhardt also acknowledged that she had withheld information about two previous marriages on her adoption application, the opinion said.

Kratovil said he argued that remaining with Bernhardt and her two young sons, one of them also adopted, was best for Deborah.

"The child is a member of the family, and uprooting her, according to eminent psychologists and psychiatrists who testified, would be devasting, just disastrous," Kratovil said yesterday.

As to Bernhardt's failure to tell the agency about the separation, Kratovil maintains that at that time of the placement, the Bernhardts "were still trying to work things out to patch up the marriage.

"She was scared as hell. She knew there was a good chance if she went to the agency and told them of the separation, it would be a severe blow against the adoption being finalized," he said.

The Court of Special Appeals panel yesterday upheld the lower court's finding that the Texas agency properly withheld its consent to adoption.