Set List collector field value depending on Lookup Select Box field value

[ss123]

Hi! 

I have a requirement where we need to automatically set a default value in List Collector field based on a Look up Select box field value.

For example: 

Lookup select box field name= u_global_group

Lookup from table = sys_choice

List Collector field name = other_practice

List table = sys_choice

If the 'u_global' value selected is "Tax", then the 'other_practice' value should be "Tax" also.

TIA.