I have a Jensen unit in our TT. I cannot BT from my phone to the Jensen while using another seperate BT speaker. Like yours, our factory speakers stink. But I was messing around one day seeing if I could get it to work. You can only do one at a time.
BUT, some JBL BT speakers can use multiple speakers of of the same source. I have a JBL flip 3 and with a free app from JBL you can connect multiple (3 maybe) JBL flip 3 speakers off the same source and all play at same time and in sync.
Otherwise I have tried any of the BT splitters that others have posted. The factory stereo is bad enough where I don't use it at all. But we just got the camper this year and I haven't made any improvements to it yet. I have to get better reception from the antenna and I will be replacing all the garbage speakers.
