Hi cjpsl and welcome to the forum
As IVA are individual voluntary arrangements, it it totally in order for you and your wife to make separate applications. But I do not think that your creditors would be too happy to see that you are funding your wife's mortgage, unless this was in lieu of child maintenance.
If you could post some more information about your case we can assist further.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
To have me propose an IVA for you, please visit:
http://www.melaniegiles.com/ivaEnquiry.asp
See customer feedback at:
http://www.iva.com/iva_companies/IVA_Advice_Bureau.asp