Q: My granddaughter lived with me from age 1 month to almost 5. Her parents now have 50/50 custody. She is now 8 and hates.

A: In order for you to sue for custody you would have to have what is called standing.

It is likely that too much time has passed in order for you to have standing. Texas Family Code Section 102.003 (the standing statute) provides, in relevant part:

(a) An original suit may be filed at any time by:

...

(9) a person, other than a foster parent, who has had actual care, control, and possession of the child for at least six months ending not more than 90 days preceding the date of the filing of the petition;

...

(11) a person with whom the child and the child's guardian, managing conservator, or parent have resided for at least six months ending not more than 90 days preceding the date of the filing of the petition if the child's guardian, managing conservator, or parent is deceased at the time of the filing of the petition;

There is another "standing" statute for grandparents to obtain custody, but you would practically have to show child abuse in order to get it. Section 102.004 provides:

(a) In addition to the general standing to file suit provided by Section 102.003 , a grandparent, or another relative of the child related within the third degree by consanguinity, may file an original suit requesting managing conservatorship if there is satisfactory proof to the court that:

(1) the order requested is necessary because the child's present circumstances would significantly impair the child's physical health or emotional development;  or

(2) both parents, the surviving parent, or the managing conservator or custodian either filed the petition or consented to the suit.

(b) An original suit requesting possessory conservatorship may not be filed by a grandparent or other person.  However, the court may grant a grandparent or other person, subject to the requirements of Subsection (b-1) if applicable, deemed by the court to have had substantial past contact with the child leave to intervene in a pending suit filed by a person authorized to do so under this chapter if there is satisfactory proof to the court that appointment of a parent as a sole managing conservator or both parents as joint managing conservators would significantly impair the child's physical health or emotional development.