2. Take away the salary argument
As we have seen before, the main reason why some parents make the decision that the mother is taking most part of the parental leave is that men on average still earn a higher salary and, therefore, it brings them into a more difficult financial situation if the father takes a longer parental leave. This issue is wrong on different levels, and you can approach this on different time horizons.
On a longer term, the solution to this problem is obviously pay equality. This topic earns a whole article itself and cannot be solved by your company alone. But every company should try go ahead as a positive example. Probably the fastest move you can make to create salary equality within your company and show that you care for this topic is creating transparency over your salaries. The boldest way here would probably be to making all salaries transparent. But it can also be a solution to just make your salary structure very clear and transparent and regularly analyze if you are on the right track to reducing the gender pay gap. Also, introducing a regular salary cycle, reviewing all salaries at the same time can be a good solution as this can help aligning salaries in a better way across the company.
Something you can do for the short term (especially as you have no control over the salaries in other companies where partners might be working), is topping up the parental allowance above the state maximum of 1.800 Euro. Some companies even do that to the amount of the actual salary, like Spotify who offers every full-time employee 6 months of parental leave at 100% of their salary⁶. As another example, Einhorn pays their employees a salary raise of 400 Euro net per child⁷. In the best case, this eliminates the salary argument in the parental leave discussion but at least it will give parents more flexibility in planning their parental leave.