The H1 details all costs of the financial remedy proceedings whereas the N260 is for costs you are seeking from the other side so the N260 is likely to be a portion of the costs already detailed in the H1.
There is no space on the H1 for LIP costs and I suggest you put these in the current solicitor section. Add a note to the form to make it clear e.g. "(includes LIP costs)".
You can detail costs of previously instructed solicitors in the previous solicitors section.