We didnt use them together on a regular basis for the same reason, we could never get a straight answer if you could or not.
We did do it once or twice when he was at his worst time for colic but mainly because gripe water seemed to have a calming effect on him, I think it was the fennal and seemed t help him drop off to sleep.
Once his colic seemed to mostly ease off (about 6 weeks) we droped the infacol and whent over to gripewater and then stoped that about 8 weeks.