Yes but the TS will only look at the first compleat claim, the other companies must then prove there claim to the first firms solicitors. This is where some of the smaller less honorable firmes try to make money.
The sign just 1 heir at a very low fee, race to get the paperwork to the TS, then charge the estate for the administration of going through the paperwork associated with the other heirs thus they virtually get a fee from every heir even if they have only signed 1.
F&F have it in our paper work that we will not make any additional charges to the estate, unfortunately very few others work this way. Hence the heir can think they are getting a good deal until the final accounts are seen and there are huge additional charges.