can a parent lose parental rights and how

A lawsuit can be filed requesting termination of a parent's rights for many reasons, which are listed in Chapter 161 of the Texas Family Code, for example:  (A)  voluntarily left the child alone or in the possession of another not the parent and expressed an intent not to return; (B)  voluntarily left the child alone or in the possession of another not the parent without expressing an intent to return, without providing for the adequate support of the child, and remained away for a period of at least three months; (C)  voluntarily left the child alone or in the possession of another without providing adequate support of the child and remained away for a period of at least six months; (D)  knowingly placed or knowingly allowed the child to remain in conditions or surroundings which endanger the physical or emotional well-being of the child; (E)  engaged in conduct or knowingly placed the child with persons who engaged in conduct which endangers the physical or emotional well-being of the child; (F)  failed to support the child in accordance with the parent's ability during a period of one year ending within six months of the date of the filing of the petition; and others.  The second element which must be proven is that it is in the child's best interest.  Now, this is for termination of their rights to be a parent altogether.  If you're simply asking that the parent's rights be restricted, well, the answer is two-fold.  You may file a modification of the possession and access schedule based on their lack of involvement in past.  Second, however, they're not visiting anyway, so why waste the time filing a modification of rights/possession not being used?  (Best of both worlds, so to speak, in a macabre twisted sort of way...)