how can i create a heath bar but i want this health bar to get bigger when i upgrate my char max healt and still filled 100%, i thing doing this with one progress bar inside other progress bar but they can’t have childrens 
Might be a bit complicated to try and explain in text - but when you place the health bar in, you can use bluprint to set its X size,
And for example if your players health is 100 you set it to 100(pixels) * 1, if its 200 you set it to 200(pixels *2)
In the example below pbar_HP is the name of my progress bar, and DOECharacter is the character that has the HP.
This editing is done inside the Widget blueprint.
The Purpose of this, is that for every 100 HP the progress bar will get 40 pixels longer, so if you have 150 HP it will be 60 pixels long, if you have 300 it will be 120 pixels long.
As for the fill - fill is done by % for progress bar, so if you have 100HP/100HP the bar will be 100% full.
So basically the fill will update automatically and shouldn’t be a problem.
If the value HP is 0 then bar will be 0 Pixels big,
man, you’re awesome 
thanks