Can you explain what you mean with "and I need to be on this VLAN also"?
If your DHCP-server is in VLAN 1 and the client is in VLAN X, then DHCP-relay is the feature to use.
If your client is in the same VLAN as the DHCP-server, no DHCP-functionality is needed on the L3 device (the MX) between them as the DHCP-server can directly give the client its config.