That will work just fine, you have several options:
1) Use direct outs on the channels mapped to the GigaAce card. The broadcast feed will follow any input mapping changes that happen on the C3500.
2) Map the desired channels – CDM, Dante, Surface – the the GigaAce card via the tie-line patches. You can have anything you want, from anywhere, routed anywhere. You can also mix this with #1 and use direct outs and some tie lines.
3) Use “record send” from VSC to send the channel inputs to the broadcast board. This is a little more limited, but can be setup in 30 seconds to test the concept of sending.
Commonly misunderstood, the dLive has a fully meshed patch matrix, regardless of source/target, that lets you route anything anywhere on tie lines. Inputs and mixes have restrictions on pulling from each other (aux 9 -> input 10 isn’t allowed _yet_?) but tie lines are free-for-all. You do need to be aware of some items like ME – if you pull from a channel/mix, you get the name – if you pull direct from an HA/card, no name.
Jay