I don’t think displaying the count of the records on a subform is a problem. Create a query & display it in a control on another form (sub sub form). Moving that information to the main form is the problem. You need a macro.
There are problems with getting someone else to provide you with the necessary macro code. If things change you have no way of making the necessary code changes to accommodate the changes. Secondly, it is usually best for the person writing the code to have complete access to the .odb in order to get specific information about the forms/tables/controls.
For example, to get the number of records displayed is fairly simple with this line:
iCount = ThisComponent.Drawpage.Forms.getByName("YOUR_FORM").getByName("YOUR_SUBFORM").RowCount
But even with this you can see the form & subform names are still needed. Along with this is then needed the control names for where to display on subform & what to do with it on the main form.