Transfer name to the new property title and remove the same name from existing property title

I bought 3 bedroom house with my sister-in-law and we built a 1 bedroom house on the same land so at a moment both properties under the same property title. Currently I live in 1 bedroom house and my sister-in-law lives in 3 bedroom house. Now we would like to separate two houses and land, and create new property title for 1 bedroom house, I will be only the owner of 1 bedroom house and my sister-in-law will be only the owner of 3 bedroom house. I understand we need to fill form TP1, application form AP1 and ID1(or ID3) to transfer my name to new 1 bedroom property title and than fill the form TR1, AP1, ID1(or ID3) to remove my name from existing 3 bedroom property title. Can I fill all these forms in the same time and send it to the Land Registry? I can pay for submitting 2 applications. The mortgage paid and we know about tax implications. Please give us advise how to transfer my name to new property title and remove my name from existing property title.

Oleksandr - you can do both transactions and submit them together as you state and pay the registration fees as a single payment as well if you wish to. Just make it clear on submission that the fee is for both and that they are linked https://www.gov.uk/registering-land-or-property-with-land-registry/transfer-ownership-of-your-property

Thank you Adam for your answer. Can I use only one ID form for both transactions?

Oleksandr - you may and again ensure you include a note to cross refer on both applications re the identity form(s) as appropriate

Thank you Adam. How long normally it takes for Land Registry to make decision on this type of application? Do I have to send tax calculations and proof of Capital Gain Tax or Stamp Duty Land Tax payment to Land Registry?

Oleksandr - wait times are lengthy so you should expect to wait 12+ months before processing starts. You'll need to consider SDLT as part of the process and lodge the appropriate evidence once obtained from HMRC as appropriate. It's HMRC that are concerned with CGT and we don't need those details

Thank you Adam, it was very useful information. Do you have fast track application and how long it takes?

Oleksandr - https://www.gov.uk/guidance/request-an-expedite

I found a solicitor to check forms, send it to Land Registry and calculate SDLT but solicitor said it will represent only me and my sister-in-law have to find another representative. I do not understand why do we need another representative and what is their job? We do not have any conflict of interests. Do my sister-in-law have to fill the same forms and send it to Land Registry? If so why we have to send the same forms to Land Registry? Thanks

Oleksandr - some solicitors will see it as a conflict of interest hence explaining that they can only act for one of you. Your sister in law has to be a party to the one set of forms used and have her own identity verified as appropriate

Thank you Adam. We have one set of forms (AP1, TP1 and ID1 or ID3) to create new property title for 1-bedroom house and transfer my name to that title and second set of forms (AP1, TR1 and ID1 or ID3) to remove my name from existing 3-bedroom property title. Which set of forms should I use and which one my sister in law have to use or it doesn't matter? My solicitor sent me 2 quotes (1 for 1-bedroom house and another for 3-bedroom house) with my name only, asked me to except these quotes and my sister in law not even mentioned in these quotes. If we have own representative do they have to apply for SDLT5 certificate separately?

Oleksandr - HMRC will need forms for each separate transaction I suspect. Any issues you have re representation are ones to raise with the solicitor