I have three siblings in Jamaica, who are my mother’s children.
If your mother is a US citizen, she can file for both her married and unmarried son/daughter.
Also, with regard to public charge, your siblings must be prepared to demonstrate to the consular officer that they will be able to financially care for themselves in America – they must be employable, and/or have their own financial ability to be independent.
Although your mother’s petition will be quicker than a US citizen sibling’s, it does not hurt to have both of you petition for your siblings.
She is a mediator and former special magistrate and hearing officer in Broward County, Florida.