Thank you for your question. I look forward to working with you to provide you the information you are seeking for educational purposes only.
Unfortunately, the reason the attorneys offer little hope is because of the US Supreme Court ruling in Troxel v. Granville, 530 U.S. 57 (2000). Under Troxel, the US Supreme Court held that the rights of the biological parents
to decide for and care for their child are fundamental rights (basic civil rights) which will not be disturbed unless the parents are proven unfit by clear and convincing evidence.
In order to prevail here, you have to prove both the mother
and father are unfit parents by clear and convincing evidence. That is what makes these cases so hard for a grandparent to win. The only other way to do this would be to try to convince the parents that it would be best for the children if they consented to granting you legal guardianship
and if they do so the court can award you the guardianship/custody.
Absent their agreement, if you have evidence that not only the mother (that would be the easy one based on what you said above) was unfit, but also that the father is unfit to raise the children and make decisions for them, then you could proceed to court to seek a court order of custody on that basis.