more than one odom->base_link transform

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Hi,

I have 2 nodes from third parts, both of them publish odom->base_link transform. I want to combine these 2 transforms and publish my own odom->base_link transform, since our navigation node needs this transform. If I can't modify the source code of all the nodes except my own fusion node, how can I make the whole system work on ROS? I mean combining the 2 input odometry and publish my own odom->base_link transform for navigation node?

I notice there was a discussion about similar topics. But it didn't provide an answer. http://answers.ros.org/question/19804...

Thanks a lot.

Yanming