I think I have created a inject node with your proper structure, give this a try to see if it helps to better understand or helps somehow
[{"id":"6314ec96.230b94","type":"inject","z":"fff2015f.77964","name":"","topic":"","payload":"{\"value\":{\"value\":\"7\"}}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":160,"y":600,"wires":[["32382e0c.4c5602","5b78cd5a.f54584"]]},{"id":"32382e0c.4c5602","type":"debug","z":"fff2015f.77964","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":390,"y":580,"wires":[]},{"id":"57c6ff06.9f1be","type":"ui_gauge","z":"fff2015f.77964","name":"","group":"b965a9b0.dec558","order":0,"width":0,"height":0,"gtype":"gage","title":"gauge","label":"units","format":"{{msg.payload.value}}","min":0,"max":10,"colors":["#00b500","#e6e600","#ca3838"],"seg1":"","seg2":"","x":590,"y":660,"wires":[]},{"id":"43be6616.519048","type":"inject","z":"fff2015f.77964","name":"","topic":"","payload":"{\"value\":{\"value\":\"5\"}}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":160,"y":660,"wires":[["5b78cd5a.f54584"]]},{"id":"5b78cd5a.f54584","type":"function","z":"fff2015f.77964","name":"var","func":"var temp;\ntemp = msg.payload.value;\nmsg.payload = temp;\nreturn msg;","outputs":1,"noerr":0,"x":370,"y":620,"wires":[["432b80a.f376a8","57c6ff06.9f1be"]]},{"id":"432b80a.f376a8","type":"debug","z":"fff2015f.77964","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":640,"y":620,"wires":[]},{"id":"b965a9b0.dec558","type":"ui_group","z":"","name":"Menu","tab":"7bce52b3.7d109c","disp":true,"width":"6","collapse":false},{"id":"7bce52b3.7d109c","type":"ui_tab","z":"","name":"Home","icon":"dashboard"}]
In case you should filter depending on the label, as example:
[{"id":"6314ec96.230b94","type":"inject","z":"fff2015f.77964","name":"temperature:7","topic":"","payload":"{\"value\":{\"value\":\"7\",\"label\":\"temperature\"}}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":130,"y":600,"wires":[["32382e0c.4c5602","e0aecf6c.7ba5b"]]},{"id":"32382e0c.4c5602","type":"debug","z":"fff2015f.77964","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":390,"y":580,"wires":[]},{"id":"57c6ff06.9f1be","type":"ui_gauge","z":"fff2015f.77964","name":"","group":"b965a9b0.dec558","order":0,"width":0,"height":0,"gtype":"gage","title":"gauge","label":"units","format":"{{msg.payload.value}}","min":0,"max":10,"colors":["#00b500","#e6e600","#ca3838"],"seg1":"","seg2":"","x":590,"y":680,"wires":[]},{"id":"43be6616.519048","type":"inject","z":"fff2015f.77964","name":"temperature:5","topic":"","payload":"{\"value\":{\"value\":\"5\",\"label\":\"temperature\"}}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":130,"y":660,"wires":[["e0aecf6c.7ba5b"]]},{"id":"5b78cd5a.f54584","type":"function","z":"fff2015f.77964","name":"var","func":"var temp;\ntemp = msg.payload.value\nmsg.payload = temp;\n\nreturn msg;","outputs":1,"noerr":0,"x":450,"y":680,"wires":[["432b80a.f376a8","57c6ff06.9f1be"]]},{"id":"432b80a.f376a8","type":"debug","z":"fff2015f.77964","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":610,"y":620,"wires":[]},{"id":"30c080e1.1688c","type":"inject","z":"fff2015f.77964","name":"humidity:50","topic":"","payload":"{\"value\":{\"value\":\"50\",\"label\":\"humidity\"}}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":130,"y":540,"wires":[["e0aecf6c.7ba5b","32382e0c.4c5602"]]},{"id":"e0aecf6c.7ba5b","type":"switch","z":"fff2015f.77964","name":"","property":"payload.value.label","propertyType":"msg","rules":[{"t":"eq","v":"temperature","vt":"str"}],"checkall":"true","repair":false,"outputs":1,"x":300,"y":680,"wires":[["5b78cd5a.f54584"]]},{"id":"b965a9b0.dec558","type":"ui_group","z":"","name":"Menu","tab":"7bce52b3.7d109c","disp":true,"width":"6","collapse":false},{"id":"7bce52b3.7d109c","type":"ui_tab","z":"","name":"Home","icon":"dashboard"}]
This last one as you told there is a combined sensor and I guess it will give you as "value" changing the "label" but this is just an assumption....