This is the Riley birth that I found
Births Jun 1937
Riley Jane Riley Liverpool S. 8b 126
Below is another Hughes/Riley birth for Liverpool S. up to 1945
Births Sep 1939
Hughes Michael Riley Liverpool S. 8b 113
There are another four births registered but as these people may still be alive I won't put them here. However if you go on the free bmd website, choose births, enter Hughes and Riley for mnn, put in years 1936 to 1945 and Liverpool South, the other births will appear.
I did the same for Liverpool North and came up with four births one of which is Maria's.
I don't know how many of these births will be siblings of Maria's.