The Dante card would have to be your main audio input signal source for the 1st ME-U, then your 2nd ME-U audio input would connect to an audio output from the 1st. Just remember that for the Dante link, the ME-U only works with 48khz audio, so your Dante card can only be a 64×64.
You won’t gain anymore channels of audio, only ability to connect more heads using POE directly to the ME-U.
The other option is to chain your ME heads and individually power each head.