strengthened the requirements for intervention under section 102.004 so that a grandparent or other non-parent who is unable to establish standing to bring an original suit for managing conservatorship but who intervenes in an ongoing SAPCR to seek managing conservatorship of a child, not only (1) must prove substantial past contact with the child but also (2) must prove that “appointment of a parent as a sole managing conservator or both parents as joint managing conservators would si randparents who had had actual possession and control of children for more than six months immediately prior to suit had standing under section 102.003(a)(9) to intervene in father’s suit to modify custody in order to seek managing conservatorship of children); In re R.D.Y., 51 S.W.3d at 318-19, 324-25 (<HOLDING>); In re Hidalgo, 938 S.W.2d 492, 495-96
holding that when children had resided with grandparents for several months during pendency of divorce proceedings grandparents had standing to intervene and seek managing conservatorship under former section 102004b and section 1020039 holding trial court did not err in appointing maternal grandmother as managing conservator when evidence showed grandmother had been childs primary caretaker for years father had history of criminal conduct drug and alcohol use dishonesty unemployment and instability and had abandoned and failed to support child and mother who had immoral and unstable lifestyle and had exposed child to violence asked court to award managing conservatorship to grandmother holding that maternal grandmother had standing to intervene in pending sapcr to seek managing conservatorship of child pursuant to former section 102004b and section 102004a where she had substantial past contact with child there was evidence of abuse and neglect of child by mother and mother had been arrested and had subsequently engaged in bizarre and dangerous behavior towards child had attacked grandmother with frying pan and hedge clippers and had been involuntarily committed to psychiatric center all of which established serious and immediate concern for welfare of child holding that evidence was sufficient to support trial courts best interest finding where mother allowed child to be in contact with individual who had physically abused her mother was not capable of caring for child on her own mother admitted at trial she had not found stable employment and child was doing well in her current placement holding that court could permit grandparent or other person having substantial past contact with child to intervene in pending sapcr even though original suit requesting possessory conservatorship could not be filed by grandparent or other person and further holding that stepgrandmother had standing to intervene to seek managing conservatorship of child under section 102004b and section 1020039 where natural mother abandoned child after birth parents were divorced natural father remarried father had custody of child after father died child lived first with stepmother then with stepgrandmother and mother first sought custody when child was eleven years old