GRAHAM Family Magheracross

[Fwynne]

Looking for any information on the following:
Richard Graham b 1840
William Graham b 1838
They arrived in Australia in 1852 from Magheracross travelling on the "David McIver".
Listed parents as James & Mary Graham.
Ages given on Shipping Lists were 18 & 20 but from death details they would have been 12 & 14.  They were to meet up with an Aunt Mary Hetherington in Wollongong NSW.
I have no idea if parents stayed in Ireland or came to Australia at a later date.
Any help on the above would be appreciated.
Regards,
Fran Wynne