Hi danj
Your IP would have to take account of your changed circumstances, if you decide to have a family and lose her income, but this will not necessarily mean that the IVA will continue to be viable. This is something that you must simply deal with at the time if such event occurs.
As Ivor says, your overall family income and expenditure would firstly need to be reassessed to see whether you could continue to make any form of repayments at all, and if so what impact any reduction would have on your IVA in the long term. If you need to reduce the payments, this may be possible by asking your IP to call a revised creditors meeting at which you can present amended proposals.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk