default to show last month unless one previous 3 months is selected on a chart

[AdrianLock]

I'd love some advice please tried looking all over the place but just can't quite seem to find an anwser that fits the issue.

I have KPI page. Which shows last months values and has small line chart under each KPI which shows last 3 months.  see below
Now currently we have number of date tables , in these is a field in called "is current month". This has a true or false value depending if its last month or not.  This allow us to default to the current month.  If you select from line chart  then it will filter the report accordingly to one of the other months. 

KPI Number of Calls for last month = IF(
ISFILTERED(dim_CALENDAR_CallStartDate[Monthnumber]),
COUNTROWS(fact_Call),
CALCULATE(COUNTROWS(fact_Call),dim_CALENDAR_CallStartDate[Is Current Month] = "True")
)
However this means each measure has to have this code to work.  (We have default data set across multiple reports, so dont really  want to have to recreate measures for the same thing with just this extra data for one report).

I  want away to be able to filter whole page down to either previous month or one selected from line chart.  Without use of a slicer, so it's seemless.