Hi,
In one of the projects which was recently upgraded to CRM 2016 Online Update 1, legacy form rendering was being used. So, we were analyzing how the new form rendering will affect the existing JavaScript.
One of the unsupported JavaScript that was being used was for sub-grid filtering.

The interesting thing was that it works in CRM 2016 Online Update 1 for legacy form rendering but fails in case of new form rendering (turbo form).
For turbo forms, we get the following objects as null


I couldn’t find any workaround of implementing the same in case of turbo forms. The only possible solution that I could think of is either using Quick View Form with Subgrid control inside it or through a html web resource.
Hope it helps..