Can I apply a namespace to a global named topic?

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Hi,

I want to use the namespace to several same nodes. However, the topic of the node is defined by a global name, i.e. '/topic_name'. In this case, adding ns='new_namespace' in launch file does not work. I think remapping can solve the problem, but remapping for all the nodes and the topics is a lot of work, especially when many nodes/topics exist. Is there any better way to solve the problem? Many thanks.