Custom Filter to display a custom form field

I am going to try my best to explain what I am doing.

I want to create a two page form.

One page one, I am going to have a field for the user to fill out.
One page two I want to dynamically display different options for a field based on the value on page one. I can't use the conditional logic built in based on the type of field that is on page one.

Is there a way I can use a custom filter (in functions.php) asking... If value of "input_17_1" = "myvalue" then field on page two (input_17_2) is theseoptions, else theseoptions2.

If input_17_1 = myvalue

input_17_2 = theseoptions
else
input_17_2 = theseoptions2

Hope that makes sense. I have successfully changed confirmation emails based on a selected value but am trying to change field options on a second page based on a value on the first page.

Thanks! Do you know of a page that has an example of the above being used? I'm not the best with coding but can follow examples and kinda hack it together from there :)

Thanks

Thanks, I'll see if I can find someone that is more knowledgable about the code and have them help me through this. Appreciate you pointing out the above info