jump start created problem

My son-inlaw jumped his car using my wifes 95 lumina. After his started ,while they were still connected hers (the lumina) stopped running and would re-start. What could have happened ?

This answer is coming a bit late, but for future reference: Don't ever arc jumper wires if the ignition is turned on. You can kiss the ECM good bye. You lucked out this time, that it restarted.

the proper way of jump-starting nowadays is to use the donor battery while the donor car is not running. If the battery of the car that is going to be started is really low then one can charge it from the running donor car for 10-20 minutes, then stop the donor car and use its battery in "passive" mode.

Otherwise, like it has been written
above, there is a good chance of frying the controller or, at least, the alternator's circuitry since the latter is not designed to withstand high currents typical for
starter's operation. Good luck.