Especially if they are sponsors, a max of courtesy shall be used.
Immagine the kind of mail you would like to receive as a sponsor and work backwards, discovering the needed structures to build such an email. Hint: you can also create a pdf and attach it, like one listing all the available concerts with a highlight on the ones chosen, maybe even indicating # of attendants and seat numbers.
I see what you're saying and I'm definitely creating a very courteous email... but aside from a PDF, is there any other way to do this?
If I am understanding your approach correctly, you can copy text out of a text box using the GetLayoutObjectAttribute function. This should allow you to automate using scripts.
Mixing text and merge fields on a layout, in a text layout object (I guess that's what you mean with text box) is something I use moderately, because you have a hardcoded part - the non merge field part - and I hate everything that is hardcoded. YMMV, but for me it's a PITA as I live in a country with 3 official languages and 4 national ones, but generally it's something any programmer tries to avoid if possible, especially because of the impact on updates etc.
OTOH you want to preserve the past, like in looking at old letters, so the best thing is to have a separate table with texts (pieces of text with a language field and maybe a sex field etc) and a lookup from that table which runs on the current letter / email, getting the "actual" text to be used and putting everything into a final text field via a script.
Example of separate text pieces table:
start text Sex Language
Gentile Signora *FN*, F I
Egregio Signor *FN*, M I
Sehr Geehrte Frau *FN*, F D
and so on.
When building the letter text in one field, you put these lookups together, then substitute placeholders (*FN* with actual FamilyName) and you have your final text in a field, you can put it as a whole as merge field on a layout and you can use it as source for your email.