hi, have u claimed FIS, according to
www.welfare.ie the income for a family of 6 children should be 910 euro per week. so if u claim fis u get 60% of the difference
e.g 910 - 420 = 490 * 60% = 294
so if u claim fis u should get 294 extra per week, if there is no maximum limit, i'm not sure about that
also u could claim Supplementary welfare allowance to help u with ur mortgage repayments, u have to go to ur local health service for this
hope i'm right in what im saying maybe someone else will clarify it for u