DAX YTD rate conversion value

We want to obtain a reporting YTD base on a general accounting ledger where one line is an accounting entry with an accounting date and an amount which can be in an other currency than EUR which is our reporting currency.

As we use average YTD conversion rates, our problem is how to manage conversion rates from currency to EUR in PowerBI as the currency rates we want to use to convert ALL lines regardless of their accounting date varies according to the month we select to display the year to date.

If I select in Date filter March, all lines in January, February and March should be converted to EUR using march average YTD rate.

If I select in Date filter April, all lines in January, February, March and April should be converted to EUR using April average rate

For now we did not succeed in setting a dynamic selection of the conversion rate.

Would you have any tips or could you provide assistance on this matter?