How to do a stacked bar chart with three different date columns

Hello everyone

The thing is, i got four columns each one with dates, and i want to do a stacked bar chart with these dates, the stacked bar chart is divided by months of the 2019, the values consist in counting the cells with each month, in the date columns, if the contract got the specific step, it got a data value, but if it didn't is blank, the problem is, i can put count the cells values filtering by months but, in the axis i don't know what date value to put, because, i got a date sheet but it can only get one relationship active at once, if i could get a multiple relationship or generate a generic date column so it can make the chart with the four areas o every column with the dates, it will be great, actually it only get the values of the active relationship, thanks in advance!