Set up the data like this:

In the first column put the dates for your monthly data, then in the next few columns (as many as you need) put the monthly Y values.

Then in the first column, below the monthly dates, put the dates for the daily and weekly data. Don't bother sorting it, the chart will work out fine. In the column after the monthly Y values, and lined up with the daily and weekly dates, put the daily and weekly Y values.

Your data range will include empty cells, but that's not a problem.

Now select the data and create your chart. You will see some gaps in the lines, where the daily and weekly dates fall between monthly dates, but again, it's not a problem. Right click on the chart, choose Select Data. Click the Empty and Hidden Cells button in the bottom left of the dialog, and select the option to connect empty points with a line.