Thank you so much for the quick reply. I can see now on page 4 about the power up condition.
I read it a hundred times myself and could not see that.
Yes, I am using the switches with pull up resistors connected to the gates of some 2N7000 mosfets so when the switch is off (not conducting) the fets turn the relays on. I will put a second set of mosfets after them to reverse the signal.
It will also mean that writing a "1" will turn the relays on because , although the datasheet seems to say that writing a "1" will turn off the switch, the owfs implementation seems to work the other way around.
Thanks again for the support.