Since there are Children from previous marriages or relationships, you need to specify how they are to be addressed in your Will, and/or Will of your Spouse.
This is important because Married spouses often leave all of their property to their surviving spouse, or if their spouse has predeceased them, to the Will makers Children. If you leave everything to your spouse but you have children from a previous marriage there is no requirement that the spouse leave anything to your Children.
Please state your desire, such as:
I leave x to my children of previous marriage. Everything else to Spouse.
I leave nothing to my children.
I want to treat all of the children the same.
I leave x to Spouse and everything else to my children
Or Specify how you want to address this matter.
The trust is established to provide that your trustee will manage your estate and make distributions to your children based upon their needs until the children reach a certain age. This blank is for the age of your children at which your trustee will distribute the assets of the trust to your children outright. i.e. 21, 24, etc. You decide the age at which you feel your children should be given your estate.