First thing is to make sure that they are assessing the value of the property at its correct price, property prices continue to fall. If they have assessed it an unrealistic value, you can ask for a reassessment/review.
You won't be able to just transfer it to someone else like a child, you would be considered as having deliberately deprived yourself of assets and would still have the value assessed against you.
There are a number of different ways of having a property not assessed against you. The main one is if it is your primary residence. Are you able to move into the house? If so, then it won't be assessed against you.
The other main way would be if the property was up for sale, but you have indicated that this is not an option at the minute.
Also if you were literally unable to sell the property, as opposed to just not wanting to sell it, then you could make a case that as things currently stand the property is of no value to you, and should be assessed at zero. As you stand to profit from any notional gain in value of the property then the Department aren't likely to look upon this favourably, but it might be worth a try if nothing else works, and you could appeal the decision to the Social Welfare APpeals Office if unsuccessful although that takes a year or more.
The other practical step you could take would be to sell your share of the house to the other family members. That would at least release your share of the capital, and would allow your capital to slowly deplete, therefore resulting in less of a reduction in as your funds get lower (although you will have to regularly request a review to make sure that the lower amount is assessed). Or if you used the proceeds to buy a house yourself, or pay off any outstanding mortgage that you may have, then it wouldn't be assessed against you.
Alternatively, if none of this sounds possible, then you could ask the other family members to offset your reduction by paying up a notional rent against your share of the property. After all, its their reluctance to sell that is preventing you from releasing your capital and that is costing you money.
Hope there's something in the above that is helpful.