Tenants by the entirety (TBE) is a form of ownership that is the same as joint tenancy with a right of survivorship (JTWROS) except that with TBE the owners must be a married couple and that the marital unit owns the property; i.e. there are no separate interests of the two spouses as there is in JTWROS (that becomes important should a creditor try to take a share of the house for the debts of just one spouse). Stating that the property is held TBE in the deed makes things easier, but in a number of states, including Florida, that recognize TBE ownership it is sufficient that the deed states that the couple are married, e.g. referring to husband and wife; it doesn't have to expressly state that they hold it as TBE. The Florida Supreme Court has stated that in Florida there are six unities that are required to create a TBE ownership. Those unities are:
Property held as a tenancy by the entireties possesses six characteristics: (1) unity of possession (joint ownership and control); (2) unity of interest (the interests in the account must be identical); (3) unity of title (the interests must have originated in the same instrument); (4) unity of time (the interests must have commenced simultaneously); (5) survivorship; and (6) unity of marriage (the parties must be married at the time the property became titled in their joint names)
Beal Bank v. Almand and Assoc, 780 So. 2d 45, 52 (Fla. 2001). The Supreme Court then went on to state the presumption that in Florida, real estate held by a married couple is held as TBE unless a contrary intent was indicated.
In the case of ownership of real property by husband and wife, the ownership in the name of both spouses vests title in them as tenants by the entireties. See Losey v. Losey, 221 So.2d 417, 418 (Fla. 1969). Thus, "[a] conveyance to spouses as husband and wife creates an estate by the entirety in the absence of express language showing a contrary intent." In re Estate of Suggs, 405 So.2d 1360, 1361 (Fla. 5th DCA 1981) (citing Losey v. Losey, 221 So.2d 417 (Fla. 1969)).
Id at 54. Thus it is very likely that the property was held as TBE if they purchased the home during the marriage, and ownership by TBE is presumed if the deed states the ownership is by a married couple. The deed does not have to expressly state that they own it as TBE. It makes things easier in some cases if the deed does state that, but not having that stated on the deed doesn't prevent it from being held TBE. Under the TBE form of ownership, when the first spouse dies, the surviving spouse becomes the sole owner of the whole property. (Divorce will break TBE ownership.) That happens automatically at the death of the first spouse. So when the first spouse dies, his/her kids do not get a share of the home under the intestate succession law as they would if the home were held by the married couple as tenants in common (TIC). The title would be TIC if they purchased the property before they got married, though that can be fixed to create a TBE if they make the necessary changes before the first spouse dies.
The bottom line here is that if they bought the property during the marriage and they never divorced the property is going to be presumed owned TBE at the death of the first spouse unless a contrary intent was indicated on the deed. So when the first spouse dies, his/her kids have no claim to any part of the property. The surviving spouse owns the entire property the instant the first spouse dies and that property is not part of the deceased's probate estate and thus neither the intestate succession law or the will the deceased spouse can give the kids a piece of the property.
Get a copy of the deed and see a real estate or probate attorney for a review of it to determine if it is indeed TBE. It probably is, but without reading the deed and knowing all the facts I could not tell you for sure what the outcome here was. But until you see the attorney, don't get yourself all worked up that the kids are going to get a share of the house. Very likely they won't.