Help shuffling miles

I'm planning a trip to Chicago and California next June; purchasing 2 return M fares with cash and upgrading to Gs with miles. For the two of us I will need 90k miles for the upgrade and at the moment they are roughly split 20k in my FC account, 20k in my accomplice's FC account and 60k on my Amex.

I had planned to get 3rd party permission to use said accomplice's account and transfer the Amex points to my account; spoke to FC today in preparation and you can only use an equal number of miles from multiple accounts. As far as I am aware I can only transfer the Amex points to my account?

So the way I see it I have 2 options:

1 Pay £90 to transfer the 10k miles needed from the second account (20k+60k+10k=90k)

2 Buy 10k miles for £165 to give me the 90k, allowing my accomplice to keep all her miles at an additional cost of £75 (I guess depending on whether she values 10k miles or £75 more)

Or is there a 3rd option? Although they say I have to use equal amounts from each account, can I treat each sector separately? So use 20k each to upgrade LHR-ORD and then use 50k just from my account to upgrade the LAX-LHR sector? (or SFO-LHR more likely looking at availability)

I know the obvious answer is to ring them back and ask them but I guess someone on here would have an imaginative way to get around it?

You do not need equal miles in the accounts just enough miles for a sector so your 3rd option is the way to do it.

So outbound you use 20k fronm your account and ditto your accomplice

For the return you take the entire 50k from your account (after you've moved your MR points there)

There is no need to transfer or gift any miles to do all of this and a competant agent will be able to do it no bother at all.

It would be easier if your accomplice authorised you to be able to access their account though.

This is the page from the VS website re using miles from different accounts.

... Since our one way redemptions are half price of a full redemption, members can book e.g. one sector from one account, and the return sector from another account

Great news, thanks for the help!