thanks a lot this is in the right way but i prefer just 1 column with the information. is this possible?
You can do an expression that will combine them.
This will have to be a series depending on how deep you go on your parent task structure. Also, this will combine them all - so if you have a task that has a milestone and then also it lives under a parent task that has a milestone it will include both.
Feel free to edit based on your needs
displayname=Parent Milestones
textmode=true
valueexpression=CONCAT({milestone}.{name}," ",{parent}.{milestone}.{name}," ",{parent}.{parent}.{milestone}.{name})

Depending on the complexity of your structure you may want to edit this code a bit to get what you need. Just know that the first "milestone.name" is the actual task milestone if it exists, and then each parent is preceded by the corresponding number of indents with the word "parent" to pull in that parent's milestone if it exists. If you needed to add another indent it would be {parent}.{parent}.{parent}.{milestone}.{name} and so on...
This is all a little advanced so if you aren't familiar you can learn about advanced reporting here.
Additionally, something I've done previously was to add a custom form to tasks that had a calculated field for parent task milestone on it. This way it would just capture on the form what the milestone name was and then that can be pulled into reporting and views natively.