It appears that the children were removed from your fiance's care due to possible failure to protect and the siblings under the imminent danger. Your fact pattern does not reveal much. As the biological father you can file for physical/legal custody of the children. If there is an open neglect case, most likely your custody and the neglect cases would be consolidated.
You should consult an experienced DC Family Lawyer. This response does not constitute/create an attorney-client relationship. Moreover, this answer is informational only and cannot be construed as legal advise.
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