Could we have a notice saying... "by submitting an image you have recieved permission by the copy right owner to use this image or you own the right to these images"?
Nothing you do can really
prevent a lawsuit. The best you can do is avoid as much as possible the areas of greatest legal risk.
What you will
need to best avoid an infringement lawsuit is a license from the copyright holders of any work you intend to duplicate on your products. A license should be structured to give you the specific rights you will need to duplicate the copyrighted material on your product.
In addition, if what is submitted is a photograph of a person, you not only need a license from whoever owns the rights in the photo (generally the photographer) but you also need a release signed by the person or persons pictured, so you don't run afoul of their publicity/privacy rights. For family photos, this is probably not going to be vital, but all you need is one litigious relative to create a legal headache for you, so it is recommended.
There are several businesses that operate in the way you intend your business to operate, and it wouldn't hurt for you to check some websites out online. Take a look at Shutterfly, for example. Shutterfly customizes products using photos that have been submitted by consumers. When ordering a customized product, the customer must agree to Shutterfly's terms and conditions through a "click" agreement. Read over their terms and conditions (www.shutterfly.com/help/terms) to get an idea of what you may find helpful for your business.
And then, once you become familiar with how others operate their similar businesses, you can better work on your own business plan (your releases, your terms and conditions, your disclaimer). I recommend you then have everything reviewed by a professional in your area (a business attorney may be best) to make sure you have dotted all i's and crossed all t's and that your business is as safe as it can be from any lawsuit.
It is also wise to have insurance enough to cover a lawsuit, should one arise despite your best efforts to avoid one.
Good luck.