Sadly I cant as he does not have the space for a 70l, Instead I have decided that I am going to sell the 70l and use the money for a 30l.Could you swap out your 70l for your friend's 35l tank? The 35l is a great size for a siamese fighter as it gives them plenty of swimming room without them looking lost in a bigger, mostly empty, tank. Plus with it being smaller it is less intrusive in a living room so parents might enjoy it being there if it is aquascaped well
My experience with fighters is that they're happiest on their own. Some might tolerate other fish in their tank but remember that is all they are doing, tolerating them.
Also Would I be able to have a bristlenose pleco in the 125l or is that overstocking. Thanks