Can a biological father with joint custody sign for his 16 year old daughter to marry the father of her baby that's 22 even if mother won't let her?

In most jurisdictions, a biological father with joint custody may have the authority to consent to his daughter's marriage, but this often depends on local laws regarding the age of consent and marriage. Typically, if the daughter is under 18, parental consent is required, and both parents may need to agree. If the mother opposes the marriage, it could lead to legal complications, and the court may need to be involved to resolve the situation. It's advisable to consult a legal expert in family law to understand the specific implications and requirements in the relevant jurisdiction.