just add it all at once
I've just got insurance through them and they told me on a number of occasions from different people I spoke to, non-power mods are free and no fees for declaring. Just call up and tell them, they'll log it, maybe they'll send an email as don't think they'll send confirmation via post.
I was told the mid-term policy change was for things like changing car or adding drivers as they may switch you to a different insurer to get the cheapest quote.
well i hope thats the case ill confirm when they're open again and let you all know!