Now, I've just checked the How to Vote cards for every House of Reps seat Family First is running in in South Australia:
Adelaide - Liberals are put second, Labor fifth.
Barker - Liberals second, Labor fourth
Boothby - Liberals second, Labor seventh
Grey - Liberals second, Labor third
Hindmarsh - Liberals second, Labor fourth
Kingston - Liberals second, Labor fourth
Makin - Liberals second, Labor seventh
Mayo - Liberals second, Labor seventh
Port Adelaide - Liberals second, Labor third
Sturt - Liberals second, Labor sixth
Wakefield - Liberals second, Labor fourth
In every single seat that Family First are running in in South Australia, they've directed their second preference to the Liberals. There is no case where they have given Labor preference over the Liberals as you seem to believe.
I wonder why you believe this - hang on. Back in March at the South Australian state election, Labor rather sneakily distributed How to Vote Cards that made it look like Family First had given them its preferences which was not true.
I'm wondering if you've fallen for a dirty trick like that. It's designed to mislead people.
Family First will occasionally give a Labor politician preference over the coalition (they did in 2007 in two seats but only in cases where that specific Labor politician is anti-gay marriage, while their coalition opponent is pro-gay marriage.) They might also do it at some stage over another one of their core issues - but in general, they direct preferences to the coalition and they are doing so at this election in South Australia.