When does it become harassment

A couple of problems

My ex has had a full disclosure of my finances, I have answered every question put to me and provided the evidence. The latest iteration involves small sums paid into our joint account, about 20-30 per month, they come from my daughter. She sometimes (actually often) borrows small sums off me that I pay from my personal account, sometimes she pays it back but only has the joint account on her internet banking, so she pays it back into there. I have been told by the ex's solicitor to provide 12 months bank statements for the account the money comes from, I can't do that, it isn't mine, but the sums are small, I also note they are paid to a joint account not an individual account and I never make withdrawals from that account, the ex on the other hand does.

My second issue is that I made a disclosure on a form E1, because it is on-line, I made a full disclosure and added in a letter a statement of truth. The ex's solicitor is demanding I complete a form E instead, but I thought this was for the courts not a solicitor. I have made a full and honest disclosure, and made a statement to that effect, do I acyually have to complete a Form E without direction from the court. I suspect the solicitor is just trying to increase their own revenue by constantly sending letters that contain demands for information they already have.

If the account the money to your daughter is paid from is your personal account why can’t you provide 12 months statements?

Court can set a date for form E to be exchanged but if your both in agreement to exchange them now then you can do. If the court hasn’t ordered you to then you don’t have to.

They already have the 12-months worth of statements, I have disclosed everything that has been asked of me. the latest letter, yesterday asked for justification of every penny I have taken out of a cash machine in the past 12 months, details of what it was spent on. I suspect the ex's solicitor is maximising their fee income by constantly sending demands for information they already have, while at the same time refusing to address my queries on their disclosure.

Your OP says you can’t provide the bank statements.
If you have withdrawn a large amount of cash then their question is reasonable. If it is just what you have always spent on day to day costs tell them that you can’t provide detail.

To clarify, in the OP I can't provide my daughters bank statements.

Just tell them that you can’t provide them as it is your daughters account and she won’t let you have them.

A court is highly unlikely to order your daughter to provide them.

Exactly what I did. My issue is that the money from my daughter (and we are only talking £80 or so in the past year) is paid into a joint account. She has all the statements for that account and I never withdraw money from it, it is used to pay the mortgage, so the solicitor was well aware before writing the letter that this 'income' benefitted both parties not myself alone. I get frequent requests for information to justify my spending but the solicitor never appears to actually look at the information before asking for the same information a second time. I suspect they are only interested in their fee, the ex has paid 15k so far and we haven't even got close to any settlement.