A network of tax-exempt advocacy groups -- all with ties to a New York real estate investor -- is funneling millions of dollars to the campaign for a California property rights measure in a way that cloaks the identity and number of financial supporters. The intricate financial web is the source of nearly all the money used to promote Proposition 90, an initiative on the November ballot aimed in part at curbing the power of government to seize private property. The financing network has spent more than $14.6 million around the country since late last year on 20 initiative drives,...