ylevi613, there is precedent in Lubavitch that one can say maamorim without officially being the rebbe. During the 9.5-year interregnum after the Rebbe Maharash passed away, before the Rebbe Nishmoso Eden officially accepted the nesi’us, both he and his brother the Razo said maamorim. Also the Ovrutcher Rebbe would say maamorim when he would visit Lubavitch, since for various reasons he couldn’t say them in Ovrutch. It’s also my understanding, though I’m not sure, that Reb Hillel used to say maamorim. So the Rebbe saying maamorim in the absence of his shver was not an “official” acceptance of the nesi’us. Bosi Legani 5711 signalled his willingness to function as a rebbe, but unofficially.
The most obvious prerogative of a rebbe that he did NOT do was to accept panim (kvitlach) in his own capacity. Instead he would take them to read at the Ohel. Every request for a bracha was answered with “azkiir al hatziyun”. This is not the way a rebbe behaves. No other rebbe ever did this. This is the way a go-between behaves; Moshe going up the mountain to convey the people’s words to Hashem.
Also at the table he would not sit at the head; that seat was reserved for the previous rebbe, and he would sit at the right. Again this was a sign of a reluctance to publicly and officially acknowledge that he was now the rebbe.
Wearing a shtreimel would be a very public statement that he was the rebbe, so he did not do it. Therefore I don’t believe the story that circulates that he asked the old rebbetzin for it.
However, I can easily believe that had he asked she would have refused. It became public knowledge during the court case that the old rebbetzin never approved of him, and never made peace with the fact that he was the successor, to the extent that in her will she instructed that he not say kaddish for her. This was not widely known before then, which is why there is a small contingent of Nechama Dinas in Lubavitch, all born in the ~14 years between her passing and the court case, but there are few if any born since then. Once chassidim knew how she really felt about the Rebbe they stopped naming after her.
As for the Rashag, it took approximately three years for him to accept that his attempt to become rebbe had failed, but after that he was absolutely devoted to the Rebbe. When the Rebbe was not invited to Barry’s wedding, the Rashag declared that he would not go either, but the Rebbe insisted that he go and be happy. At the farbrengen before the wedding the Rashag was very emotional about the situation, and the Rebbe was encouraging him to try to be happy.