Morning ! & Hi Tony
FRANCIS [-FRANK-]CREEGAN BORN JUNE 1869 SALFORD WAS ON 1901 CENSUS WITH THE WARDEN'S 
It's an interesting study of social history of the time, that names, the spelling of them etc was treated in a completely different attitude prior to WW1.
I think, for the sake of this exercise we have to assume Frank & Francis are one of the same, as are Jane & Janet

They go on to marry sometime after 1901 (as Frank was also a widow at the time of the census in 1901) and Jane's sons take on the Creegan surname in no formal way.
Up comes WW1, by the end of which self identity has become an issue. Mothers trying to prove their sons are under age to be abroad, or/and have enlisted with an alias, don't have copies of birth certificates, and indeed some can not afford to obtain them, to prove to the authorities what they are saying !
Voting age also becomes an issue about the same time, so William and Robert choose/are forced to use their legal names.
William & Robert are brothers. Francis is their cousin-in-law (if there is such a thing !!!) but not a blood rellie - I think LOL
Nice one Mack

Wendi
