It is settled case law that the admissibility of amendments depends, among other things, on whether the amended claims converge with or diverge from the subject‑matter previously claimed, i.e. whether they develop and increasingly limit the subject-matter of the independent claim of a main request in the same direction and/or in the direction of a single inventive idea, or whether they entail different lines of development because, for instance, they each incorporate different features (T 240/04, T 1474/06, T 1685/07, T 980/08, T 1589/08, T 1690/08, T 1969/08, T 162/09, T 2513/11, T 310/17). Whether the claims of auxiliary requests converge is to be understood in the sense that the subject-matter of the lower ranking requests is further defined i.e. with the intention to counter objections with regard to the preceding requests (T 1134/11).
In T 565/07 the board ruled that although patentees too should be able in principle, under R. 80 EPC, to limit a patent's subject-matter by including the features of a dependent claim in response to objections that the granted independent claim was not patentable, if they exercised that right repeatedly in a variety of directions – e.g. by filing requests in parallel or in sequence – the board would end up having to decide in which of several versions the patent was to be maintained. That would be at odds with Art. 113(2) EPC, which required the board to decide upon "the text submitted to it … by the applicant". In other words, it was up to the patentee to decide the text for further prosecution and also one or more sets of claims which in any event had to be in line with that decision and thus its chosen direction of limitation (on this point, see T 382/96, T 446/00, T 1685/07).
In T 1685/07, the auxiliary requests, which had not been filed until after the summons to oral proceedings, said completely different things. The board ruled that, when deciding whether to admit new requests first introduced during the appeal proceedings, it was particularly important to ascertain whether the applicant or patent proprietor submitting more than one request was following a consistent line of defence in its various requests and not, particularly towards the end of the proceedings, using a "screen" of different versions of claims to create, for both the other party and the board of appeal, an obscure and unacceptable procedural situation in which they were obliged to select from a multiplicity of varying versions the one which could in the final analysis be valid.
In T 649/14 the board stated that the convergency request was not bound to the date of filing of a request. It should be met at the current state of the proceedings.
In T 100/13 a proprietor had filed divergent auxiliary requests addressing a variety of points at a very late stage in the proceedings, namely after the oral proceedings had been arranged, without stating why they should be allowed over the cited prior art. The board found that, in these circumstances, neither it nor the other party could reasonably be expected to discuss their patentability for the first time at the oral proceedings. It was up to the proprietor as respondent to show in its reply to the statement of grounds for appeal why those grounds were wrong or how amending the main or auxiliary requests could overcome the objections raised and thereby enable the thus amended claims to be taken as a basis for maintaining the patent in limited form.
In T 1750/08 the board admitted the auxiliary request because the amendment as a further limitation of a feature that underlay the opposition division's decision to maintain the patent in amended form and that was already central to the discussions in the appeal (converging request).
In T 1903/13 the board stated in its catchword that it was within the board's discretion not to admit auxiliary requests which defined subject-matter "diverging" from subject-matter of higher-ranking requests, including those requests which, in essence, were filed during the first-instance proceedings and re-filed with the respondent's reply, but were not examined by the first-instance department.
In T 1280/14, the respondent (patent proprietor) had re-filed with its reply 15 auxiliary requests that the opposition division had not examined because it had granted its main request. Although the board had already found fault in its preliminary opinion with the various alternative lines of defence formed by these requests, the respondent did not reveal until the oral proceedings that it from then on intended to pursue only two of them. Holding that it should have communicated this change to its requests in due time, i.e. no later than one month before the oral proceedings, and that its conduct had therefore been at odds with the need for procedural economy, the board refused to admit its two remaining auxiliary requests and revoked the patent.