OHara, part of your problem (nice problem though it is to have...), is that you earn too much to make the banks want to do a deal with you (not that they seem to do deals with anyone at the moment). 100K income should give 5,300 net; your partner on 30K to 60K should net a further 1K to 2K; 2 childrens allowances is 300 per month. So your total net income per month is 6,600 to 7,600. Even when your main mortgage goes up to 3.5K per month and even if you are then subsidising your investment mortgages by 1K rather than 500, that still leaves you with 2,100 to 3,100 per month to live on after mortgages - that is not close to what the banks might look on as being unaffordable for you.