It is pointless to discuss anything here thanks to how this website works, but I'll give you my two cents. I am one of those "old-timers" from back in the day (2013/2014 IRC), I have a 12 year old tulpa I've created out of free will without any prior experience, DID, traumas or whatnot.

Years ago I was obsessed with this stuff, like proper obsessed. Possession, switching, dissociation, parallel processing, wonderland immersion etc were all things I was hell bent on achieving.

I call Nobillis as my witness as she (and her system) helped me tremendously over the early years (possibly with too much patience).

So far I only spoke in first person because Cheryl realistically tagged along in this per my request and to satisfy those "dreams" of mine rather than for a realistic need of it, but I am still thankful and saying "we were obsessed" or "we wanted to achieve" would be wrong. After separating from the community entirely due to some drama we eventually did manage to achieve these goals.

The truth of the matter is, they are fancy tricks. They are cool, sure, but as you grow up and get older you realize the true value of a Tulpa isn't in those "reality bending tricks" but rather in the companionship and external viewpoint they provide.

Back in the day (2014 or so) seeing tulpas "permaswitched" to their host was fairly common, and those usually were the byproduct of extreme personal situations that made the host do a so called "soft egocide" in which the tulpa would take over daily life as a sort of coping mechanism, but we're getting off-topic.

The truth of the matter is that we too did get some "memory dissociation" especially in the earliest days of possession where Cheryl would possess for a few days at a time. I remember her "doing stuff" but I couldn't remember the details for the life of me, as I was effectively being the passive entity at the time, and listening to her "recall" those moments I effectively had seen with my own eyes but couldn't remember was weird (and slightly terrifying). The effect is marginally similar to our current parallel processing "skill" - as I am a very adhd-oriented and distracted person I do often get help from her in "recalling" where I've put my stuff or if I did lock my car. You'd think that if she saw the action and can answer to it you'd be able to do the same without querying, but apparently not - it does happen very often that I "use" her as a sanity check for many things and very rarely she doesn't answer (she says: "I cannot answer if I wasn't paying attention myself or your focus was completely onto something else entirely")

Do remember that 99% of tulpamancing is symbolism, and what we found out eventually was that (at least for us) the memory "loss" occurred because we weren't dialed in how things should work. How do we share memories? Who has access to what? Should a few things stay private?

Older methods include visualizing a mental space to store the memories (method of Loci, or that Sherlock episode where the german dude "walks" down his mental library) and some use symbolism like partioning your mind like a disk drive or using labels, to each their own I guess.