Advanced Magento Developer required

I am looking for an advanced Magento developer to make a custom modification to fix an issue which has arisen recently due to changing the tax settings in my store. I will now explain in full details. I have a Magento store (version 1.7.0.2). It is a standard Magento ecommerce store but I have also had a rather complex custom modification added to allow customers to create a gift registry within my store. A gift registry allows users to compile a list of items they desire from within my store which other people can browse and purchase items from. This is mainly used for weddings so a soon to be married couple can compile a list of items they would like for their wedding and family and friends can purchase items from the gift registry. This system has been custom coded in my magento store and works well. So just to clarify I have a standard ecommerce site and the gift registry system running within the same Magento site. If regular store items are purchased then the buyer uses the standard magento checkout procedure. When items are purchased from a gift registry, the checkout procedure has been modified somewhat. The main differences are that the shipping address and shipping method is removed for gift registry orders (because gift registry orders are not shipped but compiled and delivered at a later date) and the addition of a gift message box during the checkout procedure. The system has been working well for a number of years with no problems. Now here is the issue. I wish to change the tax settings in my store. Up until now I have had no tax rates set up within magento. I now wish to apply tax rates to certain countries. Buyers will still pay the same gross price regardless of location and I have installed a magento extension which has achieved this and now buyers can see the tax amount shown on their order (if ordering from a country where tax is applicable). The problem is that I do not wish to show the tax amount on gift registry orders, only on regular store orders. Since setting up tax rates in magento, gift registry orders now display the tax amount during the checkout and on order confirmation email. There is also a page where the gift registry owner can see items that have been purchased from the registry with item costs and that page is also incorrect now as the item costs are being shown less tax. Therefore I would like a change to the gift registry system so that tax is NOT applied to gift registry orders. I can think of two ways to achieve this. There may be an easy way because at the moment, tax is not being applied to gift registry purchases if the buyer uses the guest checkout method. This is because when checking out as a guest, the shipping address step of checkout is removed so no shipping address exists on that order and therefore no tax rate is applied because shipping country is not known. However if the buyer checks out with an account then their default shipping address is being picked up by magento during checkout and tax is being applied. So the task required is to ensure that if gift registry items are purchased and buyer has an account with a default shipping address, that address is not used on the order. When I look at gift registry orders from the magento admin panel, if guest checkout is used then shipping address is blank. I would like the same result for account holders. The other way to achieve the same result is to set up some kind of rule to ensure that if an order is from a gift registry then tax should not be applied to the order. As all gift registry orders contain a gift message but regular store orders do not, it may be possible to make a rule not to apply tax to orders where gift message exists. If you would like to apply for this job, please can you reply with which of the above methods you would use or if you have a better method I have not thought of.