Re: marriage
If the spouse is put on the petition, then following later is not an issue. There is no time lapese, and they can do it when the time is convenient for them.
However, if the nurse gets married after they are in the US, then they will need to file for them, and it will be two years. Same as for children, if they are not on the petition and included in the beginning, the wait is two years. This does not apply to new infants that you have during the processing.
So what immigration says is correct.
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