Prey model & calcium levels

Hi!  I've been feeding my 8 papillons raw for a year now...unluckily I am seriously thinking on going back to kible due to some problems with it (I guess).  We just suffered an eclampsia in one of my girls, and every time i run a blood test on any of them, calcium levels are on the lower limit, or very low.  And the Eclampsia was the top of it!!  Before ordering my good old Origen I would like to know what went wrong, since they do look good & strong, and I'd hate to see them get skinny again.

They get chicken carcasses, wings or complete chicken heads (my vet says they wont absorb calcium from them)
Once a week they get liver, plus the bits stuck to the carcasses, which are really meaty.  I add cow & pig grinded meat to that.  They also get sardines once a week.  And an egg abouth once a month since they are a picky breed and don't like it (or cheese, or yogurt or fruit or veggies...)

The bitch while pregnant got also yogurt once a week and more fish; twice a week.

My vet thinks nothing of that has enough calcium that could be assimilated and of course recommends kibble.
My husband says; maybe one day kibble and one day raw?
My pro-raw friends say; raw and supplement with calcium pills or fish oil pills or even herb pills. But I am the most "experienced" in the group, since they all started after me.
And me...well i am so worried that i have no clue what to do.  Help PLEASE HELP!

Oh!  And Barf prepared diets do not exist here in Spain...actually raw feedings does almost not exist here in Spain; people think i am the very very crazy dog lady.