Architecting DNS for users with 2 SSL-VPN connections to 2 UTM's on separate sites

Question

Hi we have an interesting scenario, We have clients using the OpenVPN client to connect to multiple (2) client sites (both UTM's) at the same time, although once we connect we have DNS issues. All users are remote and so its not viable to have an Internal DNS server in the office and although local host files work they are a pain to setup on everyone's machine. 
 As they are separate clients we don't want to connect the sites together, and I'm not sure what other options we have to fix DNS resolution for both sites when connected to both, any suggestions would be great. 
 Thanks,

DouglasFoster · Answer

There is no better DNS configuration. You want a way to say that tunnel A uses split tunnel networking and is only used for DNS for COMPANYA.LOCAL. UTM does not provide this feature, and I wonder if alternatives would either. 
 It is apparently a happy accident that you have no IP address conflicts. In the general case without coordination, this should be expected as well. 
 Politically, if Org A and Org B have not seen fit to create a tunnel between them, I don't think it is appropriate for User C, perhaps a vendor to both, to create a VPN tunnel without their full knowledge and consent. 
 What could be done, with cooperation from both organizations, is a VPN client connection to company A, coupled with a VPN tunnel from A to B that is only open to the Company A IP Pool Address range.