The best way is probably to send more information. Invent a protocol to suit yourself.
For each value, you are sending some number of bytes - more depending on the measurement precision required.
You could use an extra byte, for before each reading. You can put numbers in that byte to identify the measurement type (temperature1, voltage1, etc.)
eg. You can use the first 4 bits to code up to 16 indentifiers.
You can use the remaining bits to signal other stuff, like "begin set" and "end set", to help regain order should the data stream be temporarily interrupted. Decide basic things about this telemetry. Some schemes might only send a single addressed reading when signalled to reply, requiring 2-way communication. Others might use "One-Way-Send-It-Regardless", and let the receiving program sort it out.
Any program needs to be able to read more than a stream of readings. For each data, it needs some identifier as to what reading it is, even if it sees a byte signalling a start of a whole bunch.
There are already very good serial data bus standards, many supported directly by PIC hardware, or published code blocks to give a PIC that feature. eg. CANBUS, ProfiBUS, etc. For your need, it may help to put together a block of 4 readings, and 4 identifiers, along with unique start and stop bytes.