Boris Group or 'the' Boris Group? Is article omission an error?
Solution 1:
Names need not follow conventions. Indeed, in the case of trade names, marketers may deliberately break conventions to make them more memorable.
I see/hear nothing wrong with referring to Boris Group without a definite article. In fact, I consider this the conventional form, and find the article unusual when I come across it in names like The GEO Group or The Brilex Group. I myself work for an organization whose name is the pattern ABC Group, never the ABC Group.
If the article is considered part of the name, it is always included and generally capitalized, as with The Walt Disney Company. Otherwise, its use depends on convention, though the organization may indicate how it prefers to be referenced. We tend to say the Gannett Company even though it always refers to itself either as Gannett or as Gannett Co., without an article (e.g. Gannett Co. will report on its quarterly earnings on Thursday). On the flip side, The Ohio State University will never convince every non-Buckeye to include the preceding article; most state universities do not consider it to be part of the name.
Group is no different in this respect from other names which indicate the type of organization: corporation, company, organization, trust, firm, system, funds, brands, and so forth. Even within a single institution, the University of Pennsylvania, we can note the conflicting orthography of The Wharton School (article always included and always capitalized) and the Annenberg School (article always included and conventionally capitalized) and Penn Law (in this form, article never included, though officially it is the University of Pennsylvania Law School).
Solution 2:
The use of an article is almost always optional.
Saying the Boris Group distinguishes your Boris group from generic Boris groups, presumably lesser known, Boris groups, but that's not likely to be a problem these days, is it? (I do note that internationally, there is more than one General Electric, and more than one Prudential insurance. Budweiser beer was inspired by a beer made in Budweis, called Budweis beer, but that brewer recently bought the Anheiser-Busch company.)
Decades ago, a lawyer friend asked me why I wrote "The Defiance College" in newspaper stories instead of "the Defiance College" or just "Defiance College." I replied that "The" was part of the name used in the corporate charter, back in 1850. It doesn't make any difference, he said. One can omit the "The" in legal documents without invalidating them. By writing "The Defiance College", he said, I was coming across as a snob, effectively saying "accept no substitutes." DC isn't snobbish; it's a very friendly and informal institution that reflects the non-judgmental attitudes of the United Church of Christ, the mainline Christian denomination that founded and supports them.
So while the grammar gives you a choice, I'd recommend using a lowercase the,where it makes the sentence fall off the tongue more easily, while minimizing the "full of themselves" impression that so many organizations with group or banc in their names project that a capitalized The would cause..