GLOBAL - A director of one of Europe's major real estate fund management houses has warned that managers risk investor rebellion if they fail to resist attempts by large pension funds to seize control of multi-investor pooled funds.   The fund-of-funds specialist, who asked not to be identified, claimed smaller pension funds were losing patience with fund managers' failure to curb the tendency of some cornerstone investors to steer funds exclusively in accordance with their own interests.   In return for hard-to-raise capital, some large schemes were treating multi-investor vehicles effectively as segregated accounts - and fund managers were often too afraid of losing their capital to resist, despite their better judgement.    He claimed one fund was facing a revolt likely to hit the headlines within the next few months.   In other cases, smaller pension funds are likely to join forces in attempts to wrest control of similarly hijacked vehicles.   In a market in which investors have the upper hand, he said he was urging fund managers to withstand demands from large investors over, for example, whether, when and where to deploy capital.    "It doesn't necessarily make you popular, but that's what we're here to do," he said.