Everything acquired during a marriage is community property unless a spouse can prove (or the spouses agree) that it is separate property. Separate property is property owned before marriage, or acquired during the marriage as a gift, through inheritance, or as part of a personal injury settlement.
In short, yes, you should have an attorney to represent you in a postnuptial agreement for several reasons: To be sure you are treated fairly in the agreement. To have the agreement upheld, as a court is much more likely to say it is a valid contract if both parties were represented by counsel when they entered into it.
Texas law allows spouses wide latitude in drafting their property agreements. After a marriage, spouses may change community property to separate property and vice-versa.
Even if only one spouse's name is on the deed, any property bought during the marriage is presumed to be community property, unless it was bought with separate property funds. The spouse claiming it as separate property must prove it in court.
A partition agreement divides, or partitions, a married couple's community estate into two separate estates. It is sometimes called a post-nuptial or post-marital agreement and is similar to a prenuptial agreement, except that it is executed by a married couple.
The exceptions to community property are funds or things that are: Owned by one spouse before the date of marriage. Inherited by one spouse before, during or after the marriage. Gifted to one spouse. Property purchased with separate funds during the marriage.
Any co-owner has the right to file a partition action. A person who owns even a tiny fraction of joint property has standing to ask the court to divide the property or order a sale of the property to fairly divide the proceeds.
Every co-owner of an interest in the property (no matter how small) must agree in order for a voluntary partition to occur. The remedy when agreement cannot be reached is for one or more of the co-owners to seek a court-ordered division by means of a partition suit.
Potential solutions for dividing inherited property include selling the property and dividing the proceeds, providing siblings with co-ownership, and having one sibling buy out the other siblings.