Split column values and cast them to new dataframe rows

Question

I have a dataframe like this:

df = pd.DataFrame({'Parent': ['Stay home', "Stay home","Stay home", 'Go outside'], 
                   'Child' : ['Severe weather, heavy rain', "raining", "Windy", 'Sunny, Good weather'],  'Child1' : ['4day forecast', "NaN", "NaN", 'NaN']})

       Parent   Child                       Child1
0   Stay home   Severe weather, heavy rain  4day forecast
1   Stay home   raining                     NaN
2   Stay home   Windy                       NaN
3   Go outside  Sunny, Good weather         NaN 

I want to split the Child column where there exists more than one value on a row.

Expected outcome:

       Parent   Child            Child1
0   Stay home   Severe weather   4day forecast
1  Stay home    heavy rain       4day forecast
2   Stay home   raining          NaN
3   Stay home   Windy            NaN
4   Go outside  Sunny            NaN 
5   Go outside  Good weather     NaN 

The Child column values can be split with the .split (',') method but how to make the new rows?

Any ideas?