"I've got two sisters and they're both married and they're both much more settled into the way things are"

Ann Wilson's quote is most likely describing the truth that her 2 siblings have both discovered stability in their lives. They have both discovered someone to share their lives with and have settled into a comfy routine. This might mean that they have actually both found a job they delight in, have a home they more than happy with, and have a family they are proud of. It could also mean that they have both found a partner they love and have a strong relationship with. Ann Wilson's quote is likely revealing her affection for her sis and their capability to find contentment in their lives. It is likewise a reminder to herself that it is possible to find stability and joy in life.