How to connect multiple rf433 transmitter to receiver?
You didn't provide any links to the modules or specifications. 

The normal, no collision, method would be to poll each outstation: the controller sends out a request for data to each substation in turn and waits for a response. Some form of addressing is required. Assuming your radios can't do that you have a few choices.


Transmit continuously on different channels and have the receiver cycle through all the channels to capture the data. Since the channel switching will be out of synch with the data transmission you will have to wait for an identifiable "start of message" before reading and processing the message. Then switch to the next channel.
Transmit at random time intervals on the same channel. in this scheme each transmitter is woken up from sleep to transmit on the same channel. After transmission it goes back to sleep. if transmission times are short relative to the interval between transmissions and if the number of transmitters is not to great this could work without too many missed transmissions due to collisions.


In either case some form of error checking (by message checksum) should be used.