New Record Form Load

[Spentak]

I have a main form that has a donorID. My subform is connected to my donor ID. When my form loads how to I get a certain field in the subform to create a new record on a table. For instance:

Table1
DonorInfo

DonorID(PK)

Table2
DateTime

DateTimeID(PK)
DonorID(FK)

I need the DateTimeId to create a new record for the selected donor in the main form. How do I do this?