Changing a drawing template seems to "break" BOM table and ballooning

I have a design of packing assembly wooden and foam bits and I realise I need a sheet 2 and have used the wrong drawing format template. If I swap the template (which has a sheet 2 ) my BOM table dissapears and all the balloons lose their content. Note that If I just remove the drawing format (template) it all stays put but inserting the tempate (even the incorrect original) causes the same problem. 

Any advice to prevent me having to re-do the ballooning/BOM table ?