deed of postponment help

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I have a second mortgage with first plus that I got a deed of postponement for when we moved two years ago and changed lenders, since then I have paid £25,000 of the first mortgage amount and now want to raise some further borrowing with the first mortgage lender, will I need another deed of postponement as with the additional lending the amount will still be less than the original amount that we got one for when we moved? Worried as first plus is involved!!