Is your daughter employed, and if so does her employer offer health insurance? Is she married, and if so, is her husband employed and does his employer offer health insurance and if so, does it offer health insurance to dependents?
It will be much, much easier for her to obtain health insurance through an employer's group health insurance plan than through any other method.
If either her own or her husband's (assuming she has one) employers offer health insurance, then no less often than once per year the insurance carrier MUST allow any eligible employee and (if dependents are covered) any eligible dependents to join the health plan during what is called an Open Enrollment period. During Open Enrollment, eligible employees and any eligible dependents MUST be allowed to join the plan. They cannot be turned down for ANY reason. (Note: if she is married and looking to join her husband's plan, he MUST either join the plan or be covered already on the plan. Barring COBRA, which does not apply here, under no circumstances will a health insurance plan add a dependent without the eligible employee being covered as well.)
However, that does not guarantee that any pre-existing conditions will be covered. Not all insurance plans exclude pre-existing conditions, but if the hypothetical plan we are talking about does, she could be excluded from coverage on any conditions for which she has been treated during the lookback period. At the Federal level the lookback period is 12 months; your state MAY have a shorter one. From what I know of Texas law I wouldn't count on it. Your state insurance commission will know.
At the end of twelve months of coverage, all pre-ex conditions will be covered. A pre-ex condition cannot be excluded for longer than 12 months. (18 months in some, very limited circumstances).
There is no guarantee when an Open Enrollment period might be. While many employers offer Open Enrollment during the month of December for a January 1 coverage date, the only thing that is required by law is that an Open Enrollment period exist, not when it happen. It is generally tied to the benefit year. Traditionally the benefit year runs either January-December or July-June, but it can legally be any 12 month period the employer wants.
The employer is not under any circumstances required to allow an existing employee to join the plan outside of an Open Enrollment period. The ONLY times an employee is guaranteed entrance to the health insurance plan is at the time of their initial eligibility (usually at some point within 90 days of hire) or during Open Enrollment. In fact, if the employee's share of any premiums is taken out pre-tax or if pre-tax is an option, then the employer is prohibited by law from allowing any new enrollments to the plan outside of those two points.
If she (or her hypothetical husband) is not employed and/or her/his employer does not offer health insurance (or his employer does not offer health insurance to dependents) then it's going to be extremely difficult, if not impossible, for her to obtain health insurance. Many (if not most or even all)states (I do not know specifically about Texas) offer a plan that is available to hard-to-insure individuals. Often it is through Blue Cross Blue Shield but as I said, I have no specific knowledge about Texas. I can offer no information about potential premium cost. Talk to your state insurance commission. They should be able to tell you what options exist.
The only other suggestion I can offer is that she look into whether or not she qualifies for Medicaid.
